Add quick sanity check at start of state, do not attempt to do anything unless salt.gitfs.gitpython exists to check for install_from_source within

Some Unix variants name GID 0 "wheel".  Unfortunately, one cannot
specify this group by ID, because Python conflates integer 0 with
boolean False, nor can one specify this group using the string '0',
because of assumptions in the Salt or Python codebases regarding group
names.

Signed-off-by: Rene Jochum <rene@jochums.at>

This reverts commit b03831c0b0.

This reverts commit 14b466e022.

Done at the maintainer's request.

This change tweaks the GitPython package installation state to support
alternate package names (on FreeBSD, it's called "py27-GitPython").
Also, on FreeBSD salt-ssh is included in the "py27-salt" package by
default, requiring an update to `distro_map`.

* Install pygit from package
* Add Official Salt ZeroMQ 4 COPR repository

Note that Salt itself is assumed to already to be available to the system via yum, via EPEL for example

Add modules for gitfs dependencies and documentation for how to use them.