WebStyle: debug-toolbar display condition fix

* The Flask debug-toolbar is shown iff it is added in CFG_DEVEL_TOOLS and
  CFG_DEVEL_SITE == 9 (shown to ALL users), or the current user is super
  admin (regardless of CFG_DEVEL_SITE).

Signed-off-by: Adrian Tudor Panescu <adrian.tudor.panescu@cern.ch>
Reviewed-by: Jiri Kuncar <jiri.kuncar@cern.ch>