Change drupal login to (ixp-agnostic) portable cms login

This is optimistically done in case someone (me?) gets enthusiastic enough to add (configurable) handling for other CMSes, in addition to Drupal. Either way the more generic wording can't hurt. Also, perhaps you will prefer to find another wording than "superuser" but I guess either way you prefer to de-INEXify the text (let me know if you want me to tweak that bit differently)...