This patch contains the l3 agent extension and agent part code.
This patch introduce a new l3 agent extension named "port_forwarding",
to process the binding of the port forwarding resources, manage its own
floatingip configuration on router interface and floatingip status.
Currrently, we support all Neutron Router reference implementations.
This extension uses the period router sync task and PortForwarding OVO
rpc.
* The main idea about this new extension is using the generic router sync
rpc to maintain the host port forwarding resources,
* For a single port forwarding create/update/delete, process it one by one
in smaller scope for forbidding refresh the iptables with a larger
scope frequently.
Partially-Implements: blueprint port-forwarding
Partial-Bug: #1491317
Change-Id: Ic56e67d428f6177099c285a9d1bccabc1e710f2b
de9b39ed2c