Add Jinja docs and examples

* Adds if, for, macro, and import examples to salt.renderers.jinja
Allow matching of the sys module without also matching sysctl.

Also specifying "sys." (ending dot) will work correctly.
Update Contributing.rst

Fix path to http://docs.saltstack.org/en/latest/topics/community.html#sending-a-github-pull-request
fix bug: mod_watch restart service in test mode
fix pep8
Merge pull request #3613 from agjohnson/bug-2037-jinja-doc

Add Jinja docs and examples
Merge pull request #3614 from holmboe/fix-selection-in-sysmod

Allow matching of the sys module without also matching sysctl
Merge pull request #3616 from holmboe/patch-1

Update Contributing.rst
Merge pull request #3617 from giantlock/develop

fix bug: mod_watch restart service in test mode
restructured text formatting...

fixed invalid formatting.
Merge pull request #3619 from ydavid365/patch-5

corrected text formatting... rhel instructions.
hacking on osx. a few typos. more 1st person nuke.

removed more of the first-person stuff. referred to the new osx docs for specific info.
Merge pull request #3621 from ydavid365/patch-5

hacking on osx. a few typos. more 1st person nuke.
Merging in changes from #3594
Merge pull request #3622 from techhat/iptables

Merging in changes from #3594
add the wmi stuff
Add new wmi context manager to win_network.py