CYB-217 Enable detailed view & allow videos to be played

Adding video processing for the Gallery.  Based on earlier work by @coyote with additions by @christianv and further modifications again by @coyote

* First commit below consists entirely of @christianv's work (from christianv/datacultures branch CYB-217 commit 5bb93e0d55c5a720848b7ae358fa1f99b278b2ea)
* Second commit is a cleanup of @christianv's ruby work by @coyote

[CYB-217 Enable detailed view & allow videos to be played](https://jira.ets.berkeley.edu/jira/browse/CYB-217)