make it useful from /usr/bin/ansible and the API.  Also some minor style fixes.

first_if_available and yum fixes

add first_available_file look up to _execute_template and _execute_copy
to runner.

add this data to playbook handler so it can be included into module_vars

When running the service module via sudo, `$PATH` didn't contain `/sbin`,
so the service binary couldn't be found.  This just runs `/sbin/service`
directly.  Output is spewed to stderr on error.

Added `list=status` to include the output of `service <cmd> status`.

[devel] ansible-playbook hangs if not passed --extra-vars

ansible-playbook release-my-app.yml --extra-vars="version=123"

And make $version available in the playbook without re-editing the file

Return the octal mode of a file instead of decimal.

Service module crashes if args has no "=".

Selinux -- more fun

Use socket.getfqdn() to fix issue #243

When running on lots of hosts with a large login banner on a slow network, it was still possible that the first recv() didn't to pull in the sudo password prompt, and sudo would fail intermittently.  This patch tells sudo to use a specific, randomly-generated prompt and then reads until it finds that prompt (or times out).  Only then is the password sent.  It also catches `socket.timeout` and thunks it to a more useful `AnsbileError` with the output of sudo so if something goes wrong you can see what's up.

This adds selinux_mls_enabled() and selinux_enabled() to detect a)
whether selinux is MLS aware (ie supports selevel) and b) whether
selinux is enabled.  If selinux is not enabled, all selinux operations
are punted on -- same as if python's selinux module were not available.
In set_context_if_different(), I now iterate over the current context
instead of the context argument.  Even if the system supports MLS, it
may not return the selevel from selinux.lgetfilecon().  Lastly, this
drops selinux_has_selevel() in lieu of the current approach.

Do not override the value of user and hostname.

Do not override the value of user and hostname.
Get port and identityfile only.

Fix issue #227

Unify normal and sudo remote exeuction.

Commit SHA: 87b1cf45 that put temp files in `$HOME/.ansible` instead of `/home/<user>/.ansible` was producing a directory literally called `$HOME` (no expansion) with non-sudo remote execution.  I'll take the blame for this one, as `ParamikoConnection.exec_command()` was not using the shell for non-sudo commands.  This does sudo and non-sudo execution the same way, using the shell, so environment variables should get expanded.

Older versions of selinux, such as that deployed on rhel5, only return a
context of user:role:type instead of user:role:type:level.  This detects
whether the tuple has three elements (old-style) or four.  If the
old-style, it keeps the secontext list at three elements.

fix for issue #230 - handle template taking 3  args

Bugfix for issue #229

Use the $HOME env var instead of hard coding /home/<username>

Support YAML list of hosts in playbook.

Reading the docs, I was a bit confused as to how to specify multiple hosts/groups in a playbook.  Being YAML, I assumed a normal YAML list would work:

    ---
    - hosts: [host1, host2]

But this crashes when inventory._matches() assumes hosts is a string.  This patch just checks if hosts is a list, and turns it into a string joined by ';'.

runner._chain_file_module() calls .get() on error string

runner._return_from_module() normally returns a list (?) of `[str,bool,dict,str]`, but on error it returns `[str,bool,str,str]`.  runner._chain_file_module() then tries to call .get() on the third item (`data2`), which fails when it's a string.  This patch only accesses `data2` if the return value was `ok`.  It might be better to return consistent types in both cases, but I'm not sure where/how else the return value is used.

handle issues when the hostlist is inadvertently set executable