fix migration bug

1. Added empty arrays for instances & volumes when a project is created for migration.  This allows the project to be interacted with (and viewed) optimistically, before the migration process is finished.
2. Removing a project resource (admin only feature to intentionally put the resource into the NullProject space) now adds it back to the NullProject on the client side (again, optimistically assuming it migrates into the null space on the server side following a successful action).