Should show a loading indicator while users are waiting

[Yankuan Zhang]

There is a 10-second time of period for waiting with the black screen until the resource is loaded and starts to play. Should add an indicator for users saying that resource is loading. Appear and disappear with animations.

		// showing loading indicator 
		//: add indicator w/ animation
		player.on('canplay', () => {
			// remove indicator w/ animation
			console.log('canplay!');
		});