Added more stuff

1. Added radiant and dire tower & rax methods
    I took your suggestion and wrote these methods to return a hash, the keys being tower names and values being :alive and :dead symbols.  I could change the keys to be symbol as wells, but I want your feedback on this first.

2. Added the tower and barracks modules for the above methods

P.S. Is it possible for you to add a TODO list so I can know what still needs working on?