NSX: Fix newly created port's status should be DOWN

Previously when creating a port in neutron using the nsx plugin
the port status returned would be ACTIVE even if this was not the
case. Now, DOWN is returned which will be updated by the backend
when the port goes ACTIVE.

Change-Id: I600fb1292ae79146cb14c7e23170262973878de0
Closes-bug: #1279551
Merge "NSX: Fix newly created port's status should be DOWN"