Install git on all servers

Git is a useful utility that we use everywhere these days, and it's
small, so it's not a huge thing to add to base.

Since it's in base now, you no longer need to include a git package.
However, if you're doing a command that requires git first (eg:
git::clone), just require => Package["git-core"] like normal.

Change-Id: Ie76e09866edcfe3fe89009e3ccc716a70315ff1a