#1754: Fix bug preventing filters from working.
Merge branch 'SCHOLAR-3.x' of github.com:openscholar/openscholar into master7
Merge branch 'SCHOLAR-3.x' of github.com:openscholar/openscholar into master7
#1754 #1639: Restrict what media browser shows based on context.

Media Browser in the Media embed dialog will only show images, audio, video and html files.
Media Browser in the Link tool will only show local files, regardless of type.