Unable to update port as non-admin nvp plugin

The port security patch to the nvp plugin broken the ability to update a port
as a non admin user. This patch fixes that and adds a unit test for updating
a port as a non-admin user since there was not one before.

Fixes bug 1127514

Change-Id: I9ac44a8eef14e5beeee020a901615e067ed50fbe
Merge "Unable to update port as non-admin nvp plugin"