Try and make it faster
Clear imageData after draw to hit canvas
Clear cache, tabs to spaces
Update clearing of getImageData cache
Merge branch 'get-intersection-cache' of git://github.com/vmichnowicz/KineticJS into vmichnowicz-get-intersection-cache

Conflicts:
	src/Container.js
	src/Shape.js
test + refactoring
Merge branch 'vmichnowicz-get-intersection-cache'