Disallow sharing of Timespans per MPAA's request

Sharing of Timespans was deemed to be infringing on MPAA's patents
related to the Interestellar motion picture.

We were told to deny being paid to do this commit.

Signed-off-by: Alexander Berntsen <alexander@plaimi.net>
Signed-off-by: Stian Ellingsen <stian@plaimi.net>
Reviewed-by: Stian Ellingsen <stian@plaimi.net>