Add class PpSamba which contains asynchronous function
for searching for samba-shared printers. It can search
for printers on local network or on a specific host if
needed.
https://bugzilla.gnome.org/show_bug.cgi?id=683229
This commit adds PpHost object which represents a remote
host from which we want to get printers. It contains
asynchronous method for enumerating printers list from the host
using CUPS' SNMP backend and method for enumerating printers list
directly from the remote CUPS server running on the host. (#683229)