Catch PortNotFound exception during get_dhcp_port

Close-bug: 1252437

Change-Id: I3a7954b869b4f5b909c806f8e47180e1ba6ba374
(cherry picked from commit cbe91fda7b416717a23cf7b29adf8201a8c14822)
Fix check_nvp_config erroneous complaint

Add the missing ingredient to the boolean test. This is
not a straight cherry-pick from a trunk fix, as the
utility tool has been renamed in Icehouse.

Closes-bug: #1265353

Change-Id: I9eb8fc1f85b16fbae83930fa9723db1fd25eeb5d
Merge "Catch PortNotFound exception during get_dhcp_port" into stable/havana
Merge branch 'stable/havana' of https://github.com/openstack/quantum into havana/stable