closes #1800, closes #1658, closes #1855

breaking grunt tasks out into separate files to clean up the main Gruntfile. Also removed unused requires from the primary Gruntfile and making sure they are in the appropriate task file.

Firefox recently added selectedOptions support, however, unlike chrome
and other browsers, they made it read-only and have it throw an error.
In my testing (via http://jsfiddle.net/vwvdywf9/), on various browsers and platforms, just using selectedIndex was sufficient to change the selected option.

closes #1877

Test keeping text tracks between tech loads.
This does break without the previous commit.

closes #1874

On the iphone the controls attribute of the video element is always true.

@gkatsev greatly improved text track support and implemented vtt.js as the webvtt parser. closes #1749

or, you know, actually change the threshold

updated component test to account for smaller touchmove threshold

closes #1830