Previously instance ports without IP address were not shown
because api.neutron.servers_update_addresses() ignored ports
without IP address.
This commit changes servers_update_addresses() to include
a special symbol (None) representing "No IP address"
in "addresses" attribute in "server" object.
"(No IP address)" will be shown for ports without IP addresses now.
Closes-Bug: #1804016
Change-Id: I46699731ab515667b8cdf97ef68bdb8cbfe0b563