Adds migr_network_name to config sample

etc/coriolis/coriolis.conf

@@ -26,3 +26,4 @@ auth_url = http://keystone:5000/v3
 disk_format = qcow2
 hypervisor_type = QEMU
 migr_image_name_map = linux: Ubuntu 15.10, windows: Nano
+migr_network_name = private