Make playlists only visible to users with permission to see them and fix broken tests
Users can't view playlists they don't have permission to see
Restrict viewing songs to correct playlist scope
Restrict creating songs to only users who have permissions to do it
Restrict song updating to only those who have permission
Restrict destroy action to only people with permission
Restrict actions in SongsController based on permissions and hide the links in the views
Add permissions checkboxes for admins
Add creating, editing, updating, and deleting songs to assigning permissions interface for admins
Add a seeds file to create admin and a playlist