Allow a print service to specify per printer icons, description and

info-activities

The icon is loaded from the discovery session only when it is displayed
to avoid having to store too many icons in memory.

Also the icons are not maintained in the historical printers. Only if
the printers are available nice icons are shown. A historical printer is
updated with the appropriate properties (including icon) once it becomes
available.

Bug: 24135005
Change-Id: Iec389bab514b024634be8fb5fc8928371cba8740