Change IntercationManager's DOM Element

This will make it so that you can change which DOM Element the Interaction Manager is using.

We've currently have had to change the DOM Element which InteractionManager uses on two projects. (one being the mobile only http://corollatouchdrive.com). This is due to there being other DOM content on top of the Canvas element for the renderers.

Something I'd need to look into is whether this new DOM element should be sized and positioned exactly at the position of the Canvas element or should the Developer even have control over this.