Updates to architecture and UI

Simplified the architecture: there are now only three html pages necessary -- start.html (simple builder), startAdvanced.html (advanced builder with JSON) and quiz.html. Removed the seperation between "quiz from basic" and "quiz from JSON" -- the simple builder now generates simple JSON, for consistency. 

Also improved the UI on the advanced builder page: building options and JSON side-by-side, the ability to dynamically add as many new question-type fields as you want, and the ability for repeats of question types in any order. Also, auto-populating question-type selects in the same manner as done in the simple quiz builder.