Increased button sizes on Video.js control bar, to increase touchability

Depends on #474, which depends on #471.

Fixes a UX issue @wangguan59 and @gimick identified a long time ago (but that I can't find an issue for) about it being hard to tap the buttons on the video player on mobile devices. Sizes are increased here.
@jamalex 

Is this file just refactoring (i.e. Am I just merging your first file - kalite/static/video-js/video-js.css?)

Thanks!