Fix first_available_file and add test-case

Fix to user module to use self when calling group_exists

Improve the mail callback to support differing failures

Keep fireball from spreading its socket around

Since callbacks are called with different argument-types, we have to be careful. We support two different distinct cases:

 - The error information can be in one ore more of the following items (msg, stderr or stdout)
 - The res/msg value returned can be a string or a list

Fixes to the user module

Also fix missing -G on groups change

Lost section from commit 8049777

Conflicts:
	examples/ansible.cfg

+ doc tweak

Make things more reusable, correct some errors along the SSH key path

Conflicts:
	library/user

if a module returns failed in the results, don't fail unless failed is n...

Signed-off-by: Brian Coca <briancoca+ansible@gmail.com>

Improved lookup plugins

Pretty-print "msg" when task fails

Return original string for non-matched vars