Allow ansible-galaxy to install roles from URLs

ansible-galaxy can now refer to SCM URLs (git and hg at this point)
for role names
Dependencies need to use the full SCM URLs too.
Otherwise all seems to work well

Test rolesfile
```
http://bitbucket.org/willthames/git-ansible-galaxy,v1.1
https://bitbucket.org/willthames/hg-ansible-galaxy
```
(works with ssh too)

bin/ansible-galaxy

@@ -26,6 +26,7 @@ import json
 import os
 import os.path
 import shutil
+import subprocess
 import sys
 import tarfile
 import tempfile
@@ -327,6 +328,63 @@ def api_get_list(api_server, what):
         return None
 
 #-------------------------------------------------------------------------------------
+# scm repo utility functions
+#-------------------------------------------------------------------------------------
+
+def repo_fetch_role(role_name, role_version):
+    check_repo_cmd = { 'git': ['git', 'ls-remote', role_name],
+                       'hg': ['hg', 'identify', role_name]}
+    with open('/dev/null', 'w') as devnull:
+        for (scm, cmd) in check_repo_cmd.items():
+            popen = subprocess.Popen(cmd, stdout=devnull, stderr=devnull)
+            rc = popen.wait()
+            if rc == 0:
+                return scm_archive_role(scm, role_name, role_version)
+
+    print "Repo doesn't seem to be hg or git"
+    sys.exit(2)
+
+
+def scm_archive_role(scm, role_url, role_version):
+    tempdir = tempfile.mkdtemp()
+    role_name = role_url.split('/')[-1]
+    clone_cmd = [scm, 'clone', role_url]
+    with open('/dev/null', 'w') as devnull:
+        popen = subprocess.Popen(clone_cmd, cwd=tempdir, stdout=devnull, stderr=devnull)
+        rc = popen.wait()
+    if rc != 0:
+        print "Command %s failed" % ' '.join(clone_cmd)
+        print "in directory %s" % temp_dir
+        sys.exit(1)
+
+    temp_file = tempfile.NamedTemporaryFile(delete=False, suffix='.tar.gz')
+    if scm == 'hg':
+        archive_cmd = ['hg', 'archive', '--prefix', "%s/" % role_name]
+        if role_version:
+            archive_cmd.extend(['-r', role_version])
+        archive_cmd.append(temp_file.name)
+    if scm == 'git':
+        archive_cmd = ['git', 'archive', '--prefix=%s/' % role_name, '--output=%s' % temp_file.name]
+        if role_version:
+            archive_cmd.append(role_version)
+        else:
+            archive_cmd.append('HEAD')
+
+    with open('/dev/null', 'w') as devnull:
+        popen = subprocess.Popen(archive_cmd, cwd=os.path.join(tempdir, role_name),
+                                 stderr=devnull, stdout=devnull)
+        rc = popen.wait()
+    if rc != 0:
+        print "Command %s failed" % ' '.join(archive_cmd)
+        print "in directory %s" % tempdir
+        sys.exit(1)
+
+    shutil.rmtree(tempdir)
+
+    return temp_file.name
+
+
+#-------------------------------------------------------------------------------------
 # Role utility functions
 #-------------------------------------------------------------------------------------
 
@@ -680,40 +738,50 @@ def execute_install(args, options, parser):
                 print "%s (%s) was NOT installed successfully." % (role_name,tar_file)
                 exit_without_ignore(options)
         else:
-            # installing remotely
-            role_data = api_lookup_role_by_name(api_server, role_name)
-            if not role_data:
-                print "Sorry, %s was not found on %s." % (role_name, api_server)
-                continue
-
-            role_versions = api_fetch_role_related(api_server, 'versions', role_data['id'])
-            if not role_version: 
-                # convert the version names to LooseVersion objects
-                # and sort them to get the latest version. If there
-                # are no versions in the list, we'll grab the head 
-                # of the master branch
-                if len(role_versions) > 0:
-                    loose_versions = [LooseVersion(a.get('name',None)) for a in role_versions]
-                    loose_versions.sort()
-                    role_version = str(loose_versions[-1])
-                else:
-                    role_version = 'master'
-                print " no version specified, installing %s" % role_version
+            if '://' in role_name:
+                # installing from scm url
+                tmp_file = repo_fetch_role(role_name, role_version)
+                role_name = role_name.split('/')[-1]
+                role_data = None
             else:
-                if role_versions and role_version not in [a.get('name',None) for a in role_versions]:
-                    print "The specified version (%s) was not found in the list of available versions." % role_version
-                    exit_without_ignore(options)
+                # installing remotely
+                role_data = api_lookup_role_by_name(api_server, role_name)
+                if not role_data:
+                    print "Sorry, %s was not found on %s." % (role_name, api_server)
                     continue
 
-            # download the role. if --no-deps was specified, we stop here, 
-            # otherwise we recursively grab roles and all of their deps.
-            tmp_file = fetch_role(role_name, role_version, role_data, options)
+                role_versions = api_fetch_role_related(api_server, 'versions', role_data['id'])
+                if not role_version: 
+                    # convert the version names to LooseVersion objects
+                    # and sort them to get the latest version. If there
+                    # are no versions in the list, we'll grab the head 
+                    # of the master branch
+                    if len(role_versions) > 0:
+                        loose_versions = [LooseVersion(a.get('name',None)) for a in role_versions]
+                        loose_versions.sort()
+                        role_version = str(loose_versions[-1])
+                    else:
+                        role_version = 'master'
+                    print " no version specified, installing %s" % role_version
+                else:
+                    if role_versions and role_version not in [a.get('name',None) for a in role_versions]:
+                        print "The specified version (%s) was not found in the list of available versions." % role_version
+                        exit_without_ignore(options)
+                        continue
+
+                # download the role. if --no-deps was specified, we stop here, 
+                # otherwise we recursively grab roles and all of their deps.
+                tmp_file = fetch_role(role_name, role_version, role_data, options)
             if tmp_file and install_role(role_name, role_version, tmp_file, options):
                 # we're done with the temp file, clean it up
                 os.unlink(tmp_file)
                 # install dependencies, if we want them
                 if not no_deps:
-                    role_dependencies = role_data['summary_fields']['dependencies'] # api_fetch_role_related(api_server, 'dependencies', role_data['id'])
+                    if not role_data:
+                        role_data = get_role_metadata(role_name, options)
+                        role_dependencies = role_data['dependencies']
+                    else:
+                        role_dependencies = role_data['summary_fields']['dependencies'] # api_fetch_role_related(api_server, 'dependencies', role_data['id'])
                     for dep_name in role_dependencies:
                         #dep_name = "%s.%s" % (dep['owner'], dep['name'])
                         if not get_role_metadata(dep_name, options):