Issue #1401558 by exlin, Berdir, tim.plunkett: Remove the usage handling logic from file_delete().
Issue #1361226 by Berdir, aspilicious, cosmicdreams, fago: make the file entity a classed object.
Issue #152: Update views tests for file classes.
Merge pull request #132 from quicksketch/152/file_classes

Issue #152: Make the file entity a classed object.