removing (hiding for now) crop specific media
allowing url to specify sublayer as well as layer to auto-activate

visualize/#layer-name-slug now works for sublayers as well as top layers
updating Layer model and visualize view to work with updates to other mp projects

(added filterable field to Layer model and default value for
default_hash in visualize view)
updating OpenLayers imports in arcrest_example template

(release of OL3 seems to coincide with removal of OL dev stuff from
github - OL2 example, etc...)
Merge branch 'actual' into ofr