Lxc snapshot

"vagrant lxc snapshot -s test" will create snapshots of all machines in the current directory in the form "s_machine1_test", "s_machine2_test". 

To create a machine based off this snapshot, the snapshot_suffix variable needs to be set and it will search for the snapshot when doing a "vagrant up"

From the code comments on the btrfs creation logic:
+          # Treat btrfs as follows:
+          # If a snapshot suffix is specified, search for a container name with that suffix
+          # If no snapshot is found, look for the box to make a clone. 
+          # If that is not found, setup the box to be cloned. 
+          # Create the clone based on whatever snapshot was found