Specifying net_segment_type for cluster in gui (network tab). Added span element to network_tab template, with value obtained from network tab model 'net_segment_type'. Style set to italics for now - probably something nicer would be appropriate. Closes-bug: PRD-2268

Change-Id: I08dc8df499f1ae261b8b4aa51599f990669e465c
provo il primo push