(PDK-502) make the private git available to module commands

[rodjek]

Git on Windows doesn't seem to automatically find its component binaries, so we need to add them to the path in order for the vendored git to work properly.

[DavidS]

Looks solid.

Since you are already in there, another question to consider is if we really want to override a user's install, if they have a git configured? In case of a conflict, it's probably bad either way.

Feel free to merge at will.

[rodjek]

@DavidS 👍 moved the vendored git path to the end of PATH so the user's git install will take precedence if present.

[coveralls]

Coverage decreased (-0.4%) to 93.371% when pulling 2514f8b on rodjek:gh-297 into 7b3374b on puppetlabs:master.