Fix referer checks with escaped URLs

When a SP name included spaces the referer checker would fail to match
the url. It would try to return a 403 error, unfortunately this would
also trip as a return instead of an exception was used, ending up with
a 500 error being returned to the user.

Fix url checks by unquoting before comparing.
Fix error reporting by rasing an exception when needed instead of
returning.

Signed-off-by: Simo Sorce <simo@redhat.com>