Add failed_when module variable.
Implementation note: Ternery operator trick for python prior to 2.5 is used.
(test and [when_true_value] or [when_false_value])[0]
http://stackoverflow.com/questions/394809/ternary-conditional-operator-in-python#comment1466794_394887
Allow service module to manage services not ending in .service

Fixes #3417
Add Archlinux "distribution" fact
Check for link in path in utils.path_dwim_relative()

This allows an included path to be relative to a directory, if the
basedir of the original path is a symlink. In that case, the path
is normalized and the file is searched for in the normalized path.

Fixes #3312
Merge branch 'failed_when' of https://github.com/hnakamur/ansible into hnakamur-failed_when
Updated CHANGELOG for the failed_when feature
Merge branch 'archlinux-fact' of https://github.com/Schnouki/ansible into Schnouki-archlinux-fact
Merge branch 'issue_3312_role_links' into devel
Merge branch 'issue_3417_systemd_stuff' into devel
Update CHANGELOG.md