Adding msgpack example and associated libraries

Added an example page for msgpack compressed assets. This also includes the msgpack-js.js and require.js libraries. The example scene is examples/scenes/robo_pigeon.pack. Included, but not used, is the original scene (examples/scenes/robo_pigeon.js) which is JSON Object/Scene format 4 compliant.

Additionally I included a simple Python script (and the required msgpack package) that I utilized to convert the json scene to msgpack. This has been added to utils/converters/msgpack/