[notready] Create style from ...

![newstyle](https://cloud.githubusercontent.com/assets/83384/3812893/7e1efc7e-1cae-11e4-815b-dbbc01317938.gif)

How it works:

- Example styles are npm deps (mapbox-studio-default-style, mapbox-outdoors, osm-bright, satellite-afternoon)
- Example paths are loaded up here: https://github.com/mapbox/mapbox-studio/blob/new-from/lib/style.js#L474-L479
- When saving a `tmpstyle`, first copy over the src directory and then save https://github.com/mapbox/mapbox-studio/blob/new-from/lib/style.js#L103-L114
- Shows a popup modal on newstyle button

### Next actions

- [ ] roll npm packages for mapbox-studio-default-style, mapbox-outdoors, osm-bright, satellite-afternoon