Clean Up JS and Expand Responsive Video Functionality

[EricRihlmann]

Moved the Foundation responsive video functionality from the frontend in JS to the backend in PHP. Expanded the support from just YouTube and Vimeo to all WP embed supported video sites. Also, now it supports both 4:3 and 16:9 videos by only adding the .widescreen class when needed.

To test out the new functionality, make a post/page with the following content.
(Note the YouTube videos in both 4:3 and 16:9 aspect ratio.)

<h2>Responsive Video Demo</h2>

<h2>College Humor</h2>
http://www.collegehumor.com/video/7043367/awkward-at-parties-horror-movie-with-allison-williams-and-lil-rel

<h2>Daily Motion</h2>
http://www.dailymotion.com/video/x5ewmxr_bbc-dad-says-he-s-flattered-by-response-to-viral-interview_news

<h2>Funny or Die</h2>
http://www.funnyordie.com/videos/6b57f613f9/paul-shaffer-meets-artie-fufkin-from-this-is-spinal-tap

<h2>TED</h2>
http://www.ted.com/talks/rodney_mullen_pop_an_ollie_and_innovate?utm_source=tedcomshare&utm_medium=referral&utm_campaign=tedspread

<h2>VideoPress</h2>
https://videopress.com/v/kUJmAcSf

<h2>WordPress TV F</h2>
http://wordpress.tv/2016/12/07/matt-mullenweg-state-of-the-word-2016/

<h3>Vimeo</h3>
https://vimeo.com/turbinfilm/northbound

<h3>YouTube</h3>
<h4>Shortened URL youtu.be (still works)</h4>
https://youtu.be/fJQ4hQSusjE

<h4>4:3 Aspect Ratio</h4>
https://www.youtube.com/watch?v=mM5_T-F1Yn4

<h4>16:9</h4>
https://www.youtube.com/watch?v=WUgvvPRH7Oc

<h2>Twitter</h2>
Unaffected by new WP filter.
https://twitter.com/ZURBfoundation/status/842006787385565185