Metering and VPNaaS Ubuntu package names changed

For trusty / icehouse, Ubuntu has standardized the package names for the
neutron metering agent and the neutron VPNaaS agent to match the package
names used by Debian.

Change-Id: I6e9981d41ab229ae3649d66b0f84ebc0c16caf2b
Closes-Bug: #1302087
Merge "Metering and VPNaaS Ubuntu package names changed"