Added fullscreen option to IDE

New fullscreen or "zen mode" added to the code editor. 
Added a CloudPebble favicon because the lack of one was bugging me.
![cloud_pebble_fullscreen_demo](https://f.cloud.github.com/assets/137686/1969453/a5e017e4-82f2-11e3-96f8-b90afda1a7c3.gif)