feat(android): expose videoPlayer buffer

[m1ga]

Expose the Android VideoPlayer buffer event

var win = Ti.UI.createWindow();
var v = Ti.Media.createVideoPlayer({
	width: 300,
	height: 300,
	url: "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ForBiggerEscapes.mp4"
});
var lbl = Ti.UI.createLabel({top: 0});

v.addEventListener("buffer", function(e){
	lbl.text = e.percentage
})

win.add([v,lbl]);
win.open();

label at the top should fill up to 100