Add get_selections() and set_selections() for dpkg.

This module will enable to freeze a package at a certain version, with the "hold" state.
Add TODO, amend later... FIXME.
Merge my dpkg-selections branch with develop.

Resolved conflicts in modules/apt.py.
Fix merge mistake.

urllib2 and json is part of standard Python.
Use yaml.safe_load()
Add another TODO
Use code-block

As per @terminalmage suggestion.
Merge pull request #7012 from mgwilliams/lxc

lxc: use gen_mac from salt.utils
Bugfix for interacting with yum -- bug seen on CentOS 6.4, with Python 2.6 using pkg.installed.sources.
Only get the tags which match salt's version tags formatting.
Merge pull request #7015 from s0undt3ch/develop

Only get the tags which match salt's version tags formatting.
Merge pull request #7017 from pscripter/develop

Bugfix for interacting with yum -- bug seen on CentOS 6.4, with Python 2...
Add pillar generation to salt-ssh
further doc tweaks
Moved operation section nearer the top to give a high level overview
before diving in.
Don't fail if unable to change back to the old CWD.
Fix mine.send

For functions that use arguments, mine.send is broken due to bugs in
salt.utils.arg_lookup() and salt.utils.format_call(). This commit
restores proper functionality.
Add missing `CLI Example` headers to the examples.
Remove unused variables
locallize state routines for ssh based clients