Add MCE Views for audio and video. Please clear your browser cache so that you get the latest TinyMCE stylesheet.

* Move TinyMCE shortcode handling from `wpgallery` plugin to `mce-view.js`
* Force `preload="none"` when rendering media in the editor to ensure fast loading (I realize this sounds illogical)
* Move audio and video tag builder logic in `media-template.php` into PHP funcs that can be reused by any code passing `data.model` to an Underscore template
* Pause all players when moving between editor tabs and when moving from the editor to editing in the media modal.
* Rename `wp.media.audio|video.shortcode()` to the more appropriate `wp.media.audio|video.update()` that now returns a `wp.shortcode` object instead of a string.
* Add necessary MediaElement css files to `$mce_css`
* In `wp.mce.View.render()`, support multiple instances of the same shortcode
* When rendering `wp.mce.View`s, fire a ready event that passes the current MCE View root element as context 

See #27389.



git-svn-id: https://develop.svn.wordpress.org/trunk@27528 602fd350-edb4-49c9-b593-d223f7449a82