ofxiOSVideoPlayer: Load video asynchronously in ios

Hi,
When I call loadAsync on iOS, as ofxiOSVideoPlayer::loadAsync is not implemented, it will call ofBaseVideoPlayer: loadAsync instead.

I'll get a waning saying ofBaseVideoPlayer: loadAsync() not implemented, loading synchronously

But ofxiOSVideoPlayer::load(string name) does try to load the video async by calling the following function:
[self.asset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:kTracksKey] completionHandler:

So I think we are missing the implementation of:

bool ofxiOSVideoPlayer::loadAsync(string name) {
	return load(name);
}

Am I missing something? If it's correct, I can make a pull request when needed.

Start with ofxiOSVideoPlayer::loadAsync and compare it with ofxiOSVideoPlayer::load(string name), which already calls loadValuesAsynchronouslyForKeys. Verify the iOS loadAsync path no longer falls back to ofBaseVideoPlayer::loadAsync or emits the synchronous-loading warning.