Update MediaCrush module to fix several issues

The changes brought about by this include:

* Switch to MediaCrush iframe for video/audio (for the pretty custom media player)
* Add "CUSTOM" expando generation mechanic
* Trigger expandos for things like https://mediacru.sh/hash/direct and https://mediacru.sh/hash#autoplay,loop
* Fix issue rendering several MediaCrush expandos per page
* Limit width of MediaCrush expando and preserve aspect ratio if scaled

This fixes #611, #596, #595, #594, and #593