Demo asset cleanup
Demo asset cleanup

 - Flattens namespace to simplify demo app
 - Makes testAssets lowercase since it is a member and not a type
 - Adds folding comments around typedefs and callbacks to
   allow quicker access to the asset list
 - Adds missing 'source' property in asset typedef

Change-Id: If9c971bc124790ed6ad742df9369fb5a2902c091

russitto/shaka-player,tvoli/shaka-player,indiereign/shaka-player,vimond/shaka-player,vimond/shaka-player,indiereign/shaka-player,tvoli/shaka-player,ustudio/shaka-player,TobbeEdgeware/shaka-player,cmgrecu/shaka-player,cmgrecu/shaka-player,vimond/shaka-player,shaka-project/shaka-player,cmgrecu/shaka-player,ustudio/shaka-player,shaka-project/shaka-player,baconz/shaka-player,russitto/shaka-player,tvoli/shaka-player,ustudio/shaka-player,TobbeEdgeware/shaka-player,baconz/shaka-player,brightcove/shaka-player,Ross-cz/shaka-player,shaka-project/shaka-player,TobbeEdgeware/shaka-player,TheModMaker/shaka-player,TheModMaker/shaka-player,TheModMaker/shaka-player,Ross-cz/shaka-player,baconz/shaka-player,Ross-cz/shaka-player,ustudio/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,indiereign/shaka-player,brightcove/shaka-player,russitto/shaka-player,brightcove/shaka-player,TheModMaker/shaka-player