Moving to simplified command structure - removing AbstractCommand in favour of individual MongoCommandOperations
Moved find and modify commands to use MongoCommandOperation instead of AbstractCommand
Moved remaining commands to MongoCommandOperation.  Removed AbstractCommand.
Moved all the commands into the correct package
Removed MongoCommand marker interface and renamed MongoCommandOperation to MongoCommand.  Although technically it's not a command...
Simplified some of the admin code.