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
 #-------------------------------------------------------------------------------------
 
@@ -680,6 +738,12 @@ def execute_install(args, options, parser):
                 print "%s (%s) was NOT installed successfully." % (role_name,tar_file)
                 exit_without_ignore(options)
         else:
+            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:
                 # installing remotely
                 role_data = api_lookup_role_by_name(api_server, role_name)
                 if not role_data:
@@ -713,6 +777,10 @@ def execute_install(args, options, parser):
                 os.unlink(tmp_file)
                 # install dependencies, if we want them
                 if not no_deps:
+                    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'])