Layout rework

This branch does many things to address a few problems that have been with iD for a while, while also providing a better looking, tighter experience:

![screen shot 2013-06-21 at 6 02 43 pm](https://f.cloud.github.com/assets/108094/689778/5a7b6416-dabe-11e2-9da6-e6a570b22458.png)

- Moves whole UI to the left
- Reworks save button UI
- New styles for buttons and header

If we decide to move on this version of iD, here's a todo:
- [ ] Move all the map overlay stuff to the right
- [ ] Match walkthrough to new design
- [ ] Rework save button functionality: on first click, button moves down, text changes to "confim", and clicking "confirm" is what finalizes your save.
- [ ] Add account info to footer.