Improvements to speed feature

Speed feature updates:
	- No longer requires an extra SVG for button
	- Speeds can be configured as an option to the player: use speeds: [list]
	- Add speed feature to Gruntfile.js
	- Remove speed SVG from Builder.py

Track feature updates:
	- The WevVTT parsing section so that files formatted [like the ones outlined here](http://dev.w3.org/html5/webvtt/) are parsed and displayed. (Previously it was required that each timestamp be proceeded by a number). If there is a line proceeding a cue, it is treated as an identifier for that cue and it is added as a class on the element that displays the cue when that cue is being displayed.
	- Added CSS so that line breaks in the cue are honored when it's being displayed.
	- webvvt -> webvtt everywhere
	- Fixed some things JSHint was complaining about