Enable HA, DVR and router relocation in Neutron

Enable support to configure HA routers, DVR and automatic router
rescheduling in Neutron.

Note it requires PR #191 to o-p-m, and probably some other fixes
to allow all tests to pass.

Change-Id: I40761602715c16531d89da0e700358c16c302ef1
Merge "Enable HA, DVR and router relocation in Neutron"