Invalidate the loadmodel cache when collections or users are changed.
Invalidate the loadmodel cache when collections or users are changed.

Since we use a resource path to some large images, renaming a collection
or user will change that path.  As such, we need to invalidate the
loadmodel cache when that happens.

girder/large_image,DigitalSlideArchive/large_image,girder/large_image,DigitalSlideArchive/large_image,girder/large_image,DigitalSlideArchive/large_image