WIP Bootstrap 3 fixes

This is a Work In Progress with fixes for bootstrap 3 and bits to be able to wire up the editor to http://cnx.org .

Some notables:

- modals are different
- popovers are different (I'm looking at you math plugin!)
- image uploader had a typo/bug
- sections were "accidentally" draggable if you dragged the blockish inside them
- exercises had a bug that caused aloha to crash (DOMException trying to append)