Define synced_folders on V2 vm config
Upgrade V1 shared folders to V2
Make all the VirtualBox middleware aware of synced folders
Provisioners now sync folders
Change output to not include the name
Merge branch 'synced-folders'

This introduces the foundation for a new abstraction for shared folders
called "synced folders." At this point there isn't much difference
except the nomenclature for configuration purposes. In the future, this
will be a new subsystem