ResourceFileCRUC.get_resource_file now catches ObjectDoesNotExist
exception when calling hydroshare.get_resource_file, and raises
Http404.
Updated test_resourcefile:
test_resource_file_delete now works correctly
Remaining tests fail due to, I believe, limitations in the API code:
get: AttributeError: 'FieldFile' object has no attribute 'resource_file'
post/put: rf = self.request.FILES.values()[0]
	  IndexError: list index out of range