Fix gnt-network info

Fix gnt-network info

QueryNetworks() returns the uuids of the instances that are
inside a network. Since QueryInstances() uses names and not uuids
for search, we create a uuid2name dict to get each instance name
and then retrieve its nics and networks.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Klaus Aehlig <aehlig@google.com>