This commit adds method for triggerring of authentication of print jobs
to PpPrinterEntry. This is needed for asking for authentication of jobs
of a printer from the main panel.
https://bugzilla.gnome.org/show_bug.cgi?id=758170
This commit places list of jobs to separate dialog. The dialog
is updated through calling of pp_jobs_dialog_update()
from "Printers" panel because the panel is already subscribed
to cups notifications.