Added thumbnail links to attached videos.  #2513

Updated `os_files_field_formatter_view` for oembed videos.  When colorbox is absent, nothing changes.  Otherwise we get a 150px wide thumbnail of the video.  CLicking it opens a lightbox with the embedded video.

http://imgur.com/ZLmuHE2 (Ignore the green.  That's how ubuntu takes a screenshot of a flash video.)

Todo:
* Tidy up code
* Clean up appearance
  * Colorbox has unnecessary scrollbars
  * Video icon on thumbnail is hanging off the thumbnail.
* Make sure this doesn't break other videos
Cleaned up vid thumb appearance.  #2513

Fixed video-indicator css.  Instead of absolute, it's relative with a negative top margin.  Works in media_gallery too.  This positioned it for all vids, isntead of just the first.

Fixed colorbox size.  Now it wraps the video perfectly.  Video gets scaled down if height or width would be too big.

Removed extra title.  That was caused by oembed_bare.  Just plain oembed doesn't include the title.  Seems a bit backwards, but who am I to judge?

Added class to each video.  Now they have spacing and distinct borders.

Fixed scrollbars.
Hide display of media gallery description label.  #2514

Couldn't get to this setting from the UI so I wrote an update hook.  The description on media_gallery nodes was already hidden correctly, but the files on media_gallery nodes have their own description field which was set to display above.
Merge pull request #2532 from openscholar/2514-media_desc_label

2514 media desc label