merging the ui and the ngapp dirs

Zhen,

This brings together the ngApp and the ui dirs.

Simple test plan - run grunt serve, check that all of the views and interactions work ok.

Open - my courses
Books tab: displays books
Sell your copy: opens modal
Buy (n available): displays list of offers
Info tab: displays course description
Nav UBook: displays books you are selling
Revise: modal with offer details displayed
Nav Terms: Terms are displayed - they are inactive