Modify Queue to be a Template Class

[cjchanx]

• Change Queue.cpp/hpp to just Queue.hpp and define it as a template class that allows any object type to be stored in the Queue
• Use a typedef Queue Queue<Command> to ensure backwards compatibility
• Note: The non-template Queue which supports Command may be eventually modified to be it's own standalone file (or built on top of Queue) that supports automatic free of the dynamic data pointer.