There still exist references to removed "package_edit_permissions" authorization level

They were removed in a6314365ca427213caf665e148427041713f3bdc, but still exist in https://github.com/okfn/ckan/blob/master/ckan/controllers/package.py#L1030 and https://github.com/okfn/ckan/blob/master/ckan/logic/action/update.py#L906-L912

@tobes I'm assigning it to you as you were the one to remove it. It should be quick but, if you prefer, assign this back to me. Now we should use ```package_update```, right?