The count in the directory is the number of files in the directory., not the number of files in the entire subtree
Fix the number of new materials to just those visible to the current user.
Make the materials function return an ActiveRecord set instead so we can query for those which are accessible by the current user.
Ensure we only zip up the folders which the current user can see.
Merge branch 'lessonbin' of github.com:fuzzie360/coursemology.org into lessonbin