Use feature detection rather than UA string

Hello!

I'm making use of this module - and I noticed you mention in the readme that some android versions do support the video whilst others don't - I quite fancied using feature detection rather than the UA string.

I'm not quite sure what to do with quint in this case - the tests are fine when run in a browser, but the current test system does not seem to like feature detection. Sauce labs might come in for this?

[edit]: Forgot to cite this: http://diveintohtml5.info/detect.html#video-formats.

Many thanks,
Ben