Commit MarineLives customisations from Giovanni Colavizza

Giovanni Colavizza worked with Colin Greenstreet to tailor Scripto for
MarineLives transcription use.  The biggest changes include a
customised `transcribe` view which includes semantic transcription
options; some admin pages for viewing user activity have also been
added.
Add OpenLayers media view support

Add initial, basic support for OpenLayers as a media view instead of
zoom.it, with a settings option in the plugin settings and basic output
of an OpenLayers3 instance.