Gateway Bug Redux (master) 

Of course writing up the pull request post for the last bug gave me a much better idea of how to fix it.   Do-over!

This is an annoying bug that breaks gateways for anybody on newer perl versions.  The issue is that in URLPath.pm both the `quiz_mode` and `proctored_quiz_mode` path types use the `GatewayQuiz` module so when someone does `newFromModule` it could get either of them.  In the past it has always gotten the `quiz_mode` path and there were hacks to make `proctored_quiz_mode` work (like line 388 of Problem.pm) for proctored quizzes.   Now that modules are loaded in more random orders newer systems are returning `proctored_quiz_mode` for all of the url paths, even regular gateway quizzes.   This is fixed by making `ProctoredGatewayQuiz.pm` a wrapper for `GatewayQuiz.pm` so that the url types `quiz_mode` and `proctored_quiz_mode` can have separate modules.

To Test: 
-  Make a gateway quiz and a proctored gateway quiz
-  Check that the link for the gateway quiz on the problem sets page has `quiz_mode` in the url and the proctored quiz has `proctored_quiz_mode` in the url. 
-  Check that you can submit answers for both.