Made Rendr work with requirejs

@spikebrehm This PR adds RequireJs support to Rendr and example app ```05_requirejs``` that contains grunt file and modified app files.
In order to make it run, you need to augment Rendr files to work on frontend by running ```grunt init``` (as you suggested no extra boilerplate in original Rendr files on the server).
When it's done you can continue as usual with ```grunt server```.
This example works with unminified/uncombined app/rendr files as a proof of the concept (and probably dev env workflow), for the production files can be minified combined into one or few different files using grunt + r.js minification tool.

Please let me know if you have any questions/concerns. Thank you.

/cc @bigethan @jskulski