Switch AJC stylesheet to use mysite styles

-change .btn class to quiz_btn so not to conflict with Medley .btn class
-added .flatpage wrapper to use with Medley flatpage styles
-removed br tags because Medley styles have already given us plenty of
room between paragraphs
-removed padding-bottom from .questions since p tags already have 10px
padding-bottom
Style tweaks

changed positioning of "next" button and added top margin to images