2180: fork translations when their source is deleted

Only happens when you delete *all* versions of the source.  We may need to
revisit that in the future, but hopefully this is goo enough until we tear out
the forking stuff anyway.
Cleanup syntax.
Merge branch 'dev' of github.com:pculture/unisubs into dev
2164: remove redundent admin link
2194: Don't scrub to subtitle with Vimeo videos in the new editor.
Merge branch 'dev' of github.com:pculture/unisubs into dev
2192: Re-enable HTML5 videos for the beta editor.
wait for element visible, not just present
2176: Working on lock / idling functionality in the new editor.