Add integration test for apt_repository

Tests several ways to specify the repository.  For every repo added, the test
asserts that:

 * the apt-cache was updated as expected (depends on `update_cache` parameter)
 * the PPA key was installed (depends on `repo` format)
Merge branch 'unit-tests' of https://github.com/sivel/ansible into sivel-unit-tests
Require a recent enough version of pycrypto and see that playbook and vault ues it.
Add guide for Google Cloud Engine.
Add GCE guide and retool a bit to show the add_host interactions, improvements/upgrades are welcome.

Had to shoot the recently merged nova_group module in the head temporarily as it contained a dict comprehension, which means it can't work on all the platforms
and was also breaking docs builds on CentOS.  Will engage with list about that shortly.
Merge branch 'sivel-unit-tests' into devel
distutils' requires parameter doesn't work with setuptools.  Use
setuptools' instal_requires instead
Made load_balencers in ec2_lc non-required as not all ASGs require an ELB
Merge pull request #6500 from timperrett/devel

Made load_balencers in ec2_lc non-required as not all ASGs require an ELB
fixed bad detection of change on default and premature break
Fix typo in example name
Fix docs for playbooks_intro

remove unnecessary period.
Fix typo

"resort" -> "result"
Merge pull request #6501 from bcoca/acl_fix_change_detection

fixed bad detection of change on default and premature break
Merge pull request #6502 from follower/patch-1

Fix typo in example name
Merge pull request #6503 from quiver/fix-typo-playbooks_intro

Fix docs for playbooks_intro
Merge pull request #6504 from follower/patch-2

Fix typo
Fix docs for faq

- correct spelling
Merge pull request #6505 from quiver/fix-typo-faq

Fix docs for faq
Fixes and cleanup to file functions and module
- unified set attribute functions ... not sure why 2 identical functions
exist with diff names, now there are 3 while i repoint all modules to 1
- fixed issue with symlinks being created w/o existing src when force=no
- refactored conditionals, simplified where possible
- added tests for symlink to nonexistant source, with both force options
- made symlink on existing attomic (force)