Added ability to disable bosses using logic_classunlock

-Added Key "bossesenabled"
-added input "setbossesenabled"
-Updated FGD with above changed
-Cleaned up FGD
Changed function call from KeyValue to SetKeyValue
Revert to 66fead7
Merge pull request #16 from BClark09/master

Added ability to disable bosses using logic_classunlock