fdo#41760 rhbz#1038189 refresh printer list when print dialog launched

which is the the same thing the printer settings dialog does

(cherry picked from commit 02efbed152a3a9e364cdb73628af0aed0f5d6f7a)
Signed-off-by: Michael Stahl <mstahl@redhat.com>

Change-Id: I36fb9f057b66faa8c9fce5a9934ed2fb70786363