Don't rsync .vagrant into the VM

The rsync script does not exclude .vagrant when populating the test VM
with the code so if you happened to `vagrant up` the warden test VM from
the warden directory, you get your virtual machine copied into your
other virtual machine.

This simply excludes .vagrant from the sync.
Merge pull request #60 from sykesm/dont-rsync-vagrant

Don't rsync .vagrant into the VM