Fix dynamic load of metadata in exhibits from API (#7100)

* Have API lookup use an API key
* If the Has Version property is empty, don't fire off the request.
* Pull rights data from sourceResource.rights, not originalRecord.rights
Theme changes for OpenSeadragon replacement for ZoomIt

Dramatically simplifies the javascript in main.js.
Add OpenSeadragon plugin v0.3.1
Don't add non open source assets to the repo
Merge remote-tracking branch 'origin/openseadragon-redux' into openseadragon-redux