Refactored ale_interface.
Removed misplaced comment.
Added fp to remove c++ compiler warnings.
Remove case-sensitivity for ROM files

Previously, `Space_Invaders.bin` (note the caps) would exit with the cryptic "Unsupported ROM file:" error.
Separated the ale_interface into header and class files.
Added the class file for ale_interface.
Merge branch 'mhauskn/refactor' of github.com:mgbellemare/Arcade-Learning-Environment into mhauskn/refactor