replaces Factory design with a simple array of Cube objects
  * pulls THREE geometry and material out of the Cube constructor function
    * we don't need to create a new geometry for every single cube. we can
      just past that value in when we create each mesh
  * attempting to use THREE.Color to manipulate each mesh instead of creating
    a new material every time, too
  * removes unnecessary semicolons
  * moves Cube related functions up to the top, since that's what we're looking
    at most of the time, anyway