userportal,webadmin: Error dialogs don't close on enter

- When an error dialog popped up the enter key would not
  close the dialog. This patch fixes the enter key to close
  the dialog as expected.

Change-Id: Iefd72a9de81a64fd7f194252abd46a646bdcc6c5
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1143973
Signed-off-by: Alexander Wels <awels@redhat.com>