Currently the Octavia driver for neutron-lbaas is not honoring Octavia API
status codes. This can lead to a race condition where the status update
thread is behind the actual object status in Octavia.
This updates the driver to raise the appropriate status code to the
neutron API.
Change-Id: I3ec78578c941e4648d1fccfc92b349e3415015e6
Story: 2001257
Task: 5787