Improvements to the 2.2 branch

Cascading! We're relying on this awesome project to bootstrap a local, but distributed test environment and I came across a few trivial improvements that we did in our fork and saw no harm in putting in a PR:

 * Bump HBase to 0.94.15 as 0.94.13 is nowhere to be found (at least on the mirrors closest to us)
 * Upgrade Vagrantfile to the V2 Configuration API and add `vm_box_url` so a simple `vagrant up` does the job even if the precise64 box is not available yet
 * Share the tarballs across the VMs through a `tmp` directory instead of the project root and ignore, so that the git repository stays clean
 * Clean unnecessary git ignores

More than happy to do the same when 2.5 is official/stable. We're also planning on adding Pig to the mix through a new module.

Thanks for the awesome work!