Bug in the FourRooms env implementation

[ankeshanand]

It seems the code for the FourRooms env was carried over from the option-critic implementation, and thus it also has a bug that the option-critic implementation had. See: https://github.com/jeanharb/option_critic/issues/11

Also, it seems that the goal is same every episode? https://github.com/openai/mlsh/blob/master/test_envs/test_envs/envs/fourrooms.py#L60

@kvfrans It would be cool if you can clarify this?