Enable the usage of existing 'salt-call -m' option.

Currently, the ``-m`` flag for salt-call has no effect in the loaders.
This commit allows users to specify exactly the module dirs to load
given that they follow the naming conventions for 'grains', 'runners',
'modules', 'states', etc. This is a shortcut for having to refresh cache
state when using a masterless salt-call.
The pidfile is now written prior to Minion init so the process can be managed during the init phase.
add docs for new pillar and tops modules
fix inconsistency in modules/service.py docs
fix inconsistency in modules/service.py docs (for real)
Enforce a timeout (#3431) even if you get an event every time you look

If you have a fairly busy event system (lots of minions) you will always get an event ever time that you look. This causes the tag check to catch it and do a continue, so you (effectively) get stuck reading all the messages on the event bus indefinetly-- which causes the timeout to never be enforced
fix docstrings for cobbler pillar and tops modules
Updated old README with community content

As xt pointed out, this was a bit dated. I pulled replacement content
from the first paragraph in the docs and the community page on the
website.
Merge pull request #4252 from slai/develop

PID file now written prior to Minion init
Merge pull request #4262 from mgwilliams/docs

docs for new pillar and tops modules
Merge pull request #4259 from jacksontj/develop

Enforce a timeout (#3431) even if you get an event every time you look
Removing a stray print in state.py

This was really annoying when running salt-call in 0.14
Fix several docstrings
Catch possible traceback when passing incorrect lowstate to wheel system
XCP <= 1.6 should use yumpkg5
Merge pull request #4261 from whiteinge/salt-readme

Updated old README with community content
Use get to avoid an error when the function loses the retcode

Fix #4267
protect from making / absent
Merge pull request #4270 from dlindquist/develop

Fix several docstrings
Add verification for names to be a list, fix #4265
Fix a few RST problems