Refactors app into a World closure & Cube constructor function
  * cube is not getting painted in the first place
    * requestAnimationFrame problem?
Fix issue with cube no longer shower after closure spike.
  * Cube constructor variables were declared as var's. They should
    have been set with this.<variable>
  * Cube prototype was creating a THREE.Mesh with a cube's geometry
    and material, but those were null because of the first issue.
  * Move the Cube creation into a Factory method instead of something
    that the Cube does.
Merge pull request #2 from jonathanpeterwu/closure-spike

Closure spike