DrawingPane: Rewrite drawing board using sketchpad.js

https://cloudup.com/c01fk9EnbKP
IDE: Fix resizing issue of the IDE when Koding sidebar collapsed.

This is not an ideal fix because when Koding sidebar collapsed IDE sidebar changes its width automatically, it shouldn't. I will make it better when I have time. kib, bye.
Merge pull request #36 from koding/drawing-board

DrawingPane: Rewrite drawing board using sketchpad.js