Freeze exceptions for g-s-d (#766563)

[Marek Kasik <mkasik redhat com>]

Hi,

recently, I've implemented authentication of print jobs in Jobs dialog 
of Printers panel of g-c-c. This has been already pushed.
There is a follow-up of this work in g-s-d which shows a notification if 
there is a new job which needs authentication and clicking on it will 
show the mentioned jobs dialog with ability to authenticate jobs there.
The patch has been already reviewed by Felipe Borges and design was 
agreed by Allan Day. You can see a screenshot here:

https://bugzilla.gnome.org/show_bug.cgi?id=766563#c10

There are 2 new strings:

"%s Requires Authentication"
"Credentials required in order to print"

I would like to ask you for UI freeze exception and for string freeze 
exception.

Thank you

Marek