Edit Quiz: Added question type menu, and added ability to save multiple choice questions

Still left to do:

- No ability yet to view multiple choice questions yet in Take Quiz. (Take Quiz assumes all questions are fill-in.)

- No e2e tests for new functionality yet (will add after I take care of the first item).

- No ability yet to reorder choices. I tried, but couldn't get the ui-sortable directive to work from within the editquestion directive. When I try to use ui-sortable in ul.choices in editQuestion.html, sortable.js reads out the sortable options from the attribute, but when it runs scope.$eval, it returns undefined. I think there's some sort of an issue with it using the wrong scope to do the $eval.