Bump version for testing.
Implement VirtualBox provider extension for snapshots.

These changes are mainly to open up the existing VirtualBox provider and
provide additional methods for managing the snapshots of the VM. This is
my first cut at extending this class. Let's see if it works!
Ignore the binstubs.
Add a basic Vagrantfile for plugin testing.
Initial draft of the VMWare Fusion snapshotting.