Neutron refactor: Clarify use of neutron-metadata-agent
Neutron refactor: Clarify use of neutron-metadata-agent

The commit message of 2a242519f71e86416e78541826cac2b54fcd04a5 indicated
that neutron-metadata-agent was the correct name for the metadata
proxy, but parts of the code were not consistent.

Change-Id: I52f08266a169aeb9005c0f84296fc814d05b90d4

bswartz/devstack,noironetworks/devstack,bigswitch/devstack,openstack-dev/devstack,nawawi/openstack,noironetworks/devstack,openstack-dev/devstack,bswartz/devstack,group-policy/devstack,Mahito/devstack,richliu/devstack,dtroyer/devstack,group-policy/devstack,nawawi/openstack,Mahito/devstack,richliu/devstack,bigswitch/devstack,dtroyer/devstack