VID-424 Normalize video upload
Factors out the internal video file pattern recognition so that both video insertion and video upload can use it.
VID-424 Do not mark vid file deleted on WikiaVideoAdd page
This is a fix for this page and it works since this page does not have the video on it.
This whole logic does need to be reworked, however.

CC @garthwebb @jsutterfield
VID-424 Revise getVideoByUrl to getVideoFileByUrl
And a few logic cleanups
cc @garthwebb
Merge pull request #3932 from Wikia/VID-424

VID-424