email: celery error email fix

* Fixes issue with celery not sending error emails due to config
  variable ADMIN being set different by the Flask Email extension.

Signed-off-by: Lars Holm Nielsen <lars.holm.
debug_toolbar: error reporting fix

* Fixes an issue where an error message would be produced even if
  Flask-DebugToolbar was explicitly disabled via DEBUG_TB_ENABLED
  set to False.

Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>