Shapes Dropdown

More intuitive UI for adding shapes, with color fade and tooltip on hover.

![screen shot 2014-07-14 at 12 25 29 pm](https://cloud.githubusercontent.com/assets/6219591/3573648/4c074124-0b74-11e4-86ff-60627c5237ed.png)

We could possibly make this one level shallower by putting the shapes on the navbar itself, though it would take some modification of existing Bootstrap components to line up nicely on the nav.