Grabbing playbackSpeed set by UI
Replaced playbackSpeed refs
Fix runlint script so it doesn't reference a file which no longer exists

Test Plan:
- Run tools/runlint
Specify react prop types. Fixes #22.

Test Plan:
- Run tests, play with app
Grabbing playbackSpeed set by UI
Replaced playbackSpeed refs
Merge branch 'playback-speed' of https://github.com/farezv/khan-academy-fxos into playback-speed
className was accidentally omitted

while solving a merge conflict
Replacing playbackSpeed refs in test folder
Merge pull request #53 from farezv/playback-speed

Playback speed works & 'playbackSpeed' refs changed to 'playbackRate'
Add VideoJS deps
Rename conflicting role='button' for VideoJS
Upgrade video player to use VideoJS. Fixes #52, #7 and #6

Test Plan:
- Watch a video, see how cool it is.
Fix issue when leaving video page when video isn't loaded yet

videojs.dispose needed a null check on videojs because it wasn't set
yet.

Test Plan:
- Load video page, before video loads, press back.
Set volume control and play position bar colors to match domain colors

Test Plan:
- Load a few different domains and make sure the video progress and
  volume sliders have the correct colors.
remove vjs.woff since it throws some kind of error in console. Prefer the svg format.

Test Plan:
- None
Remove the dispose and explicit buffer clearing for now

After testing on a device I may need to re-enable it, but it's causing
some problems when navigating away for now.

Test Plan:
- None
Fix fonts and coloring for test prep video player

Test Plan:
- Load test prep make sure vidoe player colors are purple
- Make sure no font errors in console
Cleanup video dispose logic

Test Plan:
- Load a video, press back, load it again, press back.
Align points to the left so that volume control doesn't overlap in portrait view.

Test Plan:
- None