Improved functionality for videos and gloss revisions in admin

[susanodd]

I'm adding some functionality to the admin to

• search on lemma as well as annotation
• search on video file types that are not mp4
• fix old backup files so they have the correct video type in the file name (*)
• fix wrongly numbered backup files (the API is creating all backups as version 1 (**)
• add a restore video command for deleted media in the DeletedGlossOrMedia table (optionally put this in the media manager so a link can be given)

(*) the old bak bak files have no video type file extension
(**) the pull request that fixes the version numbering bug is not reviewed yet

@vanlummelhuizen @Woseseltops should "Apple iTunes Video (.M4V) Video" have extension MP4 or should they have M4V.

The ensure_mp4 code tested them for h264 and made the extension be "mp4".

I made an admin command that sets the extension (possibly before the bakNNN) to match the video type..