#10 Get better colors from album art

Right now, because the method is basically "locate colors within 1.5 standard deviations of the average and average them", it actually creates an average that has colors with the *widest standard deviation*, not colors that are *the most common*. So I need to use something better -- perhaps e.g. the algorithm [here](https://github.com/jariz/vibrant.js/blob/master/src/Vibrant.coffee).