neutron-metering-agent service name is wrong

In Ubuntu the neutron-metering-agent Upstart service is named
neutron-plugin-metering-agent.

Change-Id: I823f469ff3fc802d7bde40eca1f69617fd0a3307
Partial-Bug: #1284179
VPNaaS service name is wrong

In Ubuntu the VPNaaS service name and package are
neutron-plugin-vpn-agent.

Change-Id: I078227fec72133d57041501ea3d492c2c69cf8cf
Closes-Bug: #1285314
Merge "VPNaaS service name is wrong"