EDITING: Graft Aloha to the editor

**Note:** This is a PR into the `editing` branch, not `master`

Done List:

- [x] load Aloha using requirejs
- [x] enable oer block plugins (note, example, exercise)
- [x] add block styling
- [x] move titles out of the `<header>` element
- [x] hide Aloha's floating ribbon toolbar
- [x] hook simple toolbar into Aloha
- [x] add advanced block elements to toolbar
- [x] add FontAwesome or get the delete/advanced settings buttons visible
- [x] get DnD blocks (existing and new) by adding jQueryUI
- [x] add Paste button for toolbar

Some things to demo (so far):

- change the type of the note using the carrot
- delete the title of a note and then type a new one in (placeholder)
- click to add a new solution to an exercise
- try editing a table? (click tab to move around)
- toolbar operations
  - create one line of text (by pressing return a few times) and change the Heading/Subheading
  - select a word and press bold, italic, underline, subscript, superscript and then deselect one or more
  - create a list by making a line of text and clicking the link
  - indent/outdent the list by clicking indent/outdent buttons
- dragging
  - drag a new semantic element from the toolbar
  - drag an existing block in the content around (drop does work if you drop into a note/exercise/example or be precise when dropping between paragraphs)
- Copy and Paste by clicking "Copy Note" in a note, move cursor elsewhere, click "Paste" in toolbar

TODO list (probably demo-able without all of them being checked):

- [ ] get "Add Solution" working (Requires "cleaning up" the HTML before enabling Aloha)
- [ ] add Paste button
- [ ] update the title's `data-parent-label` when changing block's type via the dropdown (polyfills ; )
- [ ] upgrade Bootstrap 2.3.2 (`math`, `image`, and `link` editing depend on this)
- [ ] serialize the XHTML back into the model
- [ ] dynamically load the Aloha CSS file

**Note:** You will need to build the single-file version of Aloha by running `r.js -o build/aloha/build-profile-with-oer.js` in `bower_components/aloha-editor`.