Fix DVR to service LBaaS VIP Ports

Currently, DVR router namespaces are created only
when there is a valid VM port on the compute
node, or for the gateway-port on the service node.
But when an LBaaS VIP port is created the l3 agent
does not create a DVR namespace to service the VIP port.
This fix enables DVR namespaces to be created to
service the LBaaS VIP port.

Also, this fix enables L2 Agent running in DVR
mode, to add-in OVS rules to enable packets to
be routed to such LBaaS VIP Ports which are
resident on DVR routed interfaces.

Therefore, with this fix both East-West and
North-South traffic will be serviced by DVR
for LBaas VIP Ports.

DocImpact

Authored-by: Swaminathan Vasudevan <swaminathan.vasudevan@hp.com>
Co-Authored-By: Vivekanandan Narasimhan <vivekanandan.narasimhan@hp.com>

Change-Id: I698b971d50721fb0512a11569f7d3139d0d456f3
Closes-Bug: #1356464
Make L3RpcCallback a separate callback class

RPC has a version of itself. In Neutron a plugin implements
several RPC interface, so a single RPC version doesn't work.
In Mixin callback class approach, RPC versioning depends on
each plugin implementation and it makes harder to maintain
RPC version appropriately. This patch series replaces mixin
RPC callback of server side with a separate class.

This commit handles server-side callback of L3-agent RPC interface.
L3-agent server-side callback class is moved from db/ to
api/rpc/handlers because it doesn't involve any db operations
and defining all RPC interfaces in a single place sounds reasonable.

Note that moving other L3-agent related RPC interface class
to api/rpc/handlers will be done in a separate patch as this patch
focuses on reorganizing the server-side RPC callback class.

Partial-Bug: #1359416
Change-Id: Ie3f2c9b2ad907a1110e05fe94d42e41e93fbcaa7
Fix incorrect number of args to string format

Since there wasn't already one, also add a unittest for
PortProfileBinding and repr() functions.

Change-Id: Ibd8c5a21a7743af4c1c302495a65eeb5e45f6315
Merge "Fix DVR to service LBaaS VIP Ports"
Merge "Fix incorrect number of args to string format"
Merge "Make L3RpcCallback a separate callback class"