Have an admin utility to update the default cluster section. This
will save restarting neutron every time a cluster is added/deleted.
Admin utility command is:
nsxadmin -r firewall-sections -o nsx-update
The cluster modefs still need to be updated in the nsx.ini file
Change-Id: If750c150a1b624b5a321dc744e0f538b3a58c5b5
d85dd105b8