Dynamic Module Loader Support

Putting this here as a discussion point - I don't expect it to be accepted immediately.

I had to remove the "const" and "let" statements, for a reason I can't work out. I'm not sure if there is a compilation option I am missing here.

Other than that, this demonstrates complete dynamic loading of ES6. I only changed the "module" into its own file. We can potentially reference the external scripts (Backbone etc) as moduleIDs as well. Unfortunately this would have been done with ondemand, which is now in flux, so perhaps we can wait on this.

I completely understand though if you'd prefer this example to use a build-based system rather than this dynamic browser-based workflow. Both are completely valid scenarios.