bugs:
  - fix the permission problem uncovered by the browsertest (#6196)
  - backport changes to five.customerize

improvements:
  - direct link from viewlet manager
  - link/button in reg listing to delete customized versions again
  - memoize global registrations to speed things up (memoize.ram)
  - group views/viewlets

five.customerize:
  - unregister with two checkboxes checked needs to be fixed
