Added start and stop methods on scene for encapsulated render loop - https://xeolabs.lighthouseapp.com/projects/50643-scenejs/tickets/138-encapsulate-scene-rendering-loop-in-scene-start-and-stop-funcs
Added start and stop methods on scene for encapsulated render loop - https://xeolabs.lighthouseapp.com/projects/50643-scenejs/tickets/138-encapsulate-scene-rendering-loop-in-scene-start-and-stop-funcs

dayo7116/scenejs,tsherif/scenejs,tsherif/scenejs,dayo7116/scenejs