Changed custom controls to be the default on touch devices (!)

Previously we've relied on native controls on touch devices, but now switching to use the video.js custom controls by default.

This can be reverted by setting the option `nativeControlsForTouch: true`.

I've tested across Android, iOS, and Windows 8.1 and it all works decently. There's a few things we could improve, like the size of the controls on touch devices, but better to get this out now than wait any longer.