The current core reviewers hierarchy didn't have a place for the
parts of ML2 that weren't related to agent communication. For now
we can put all of ML2 under the built-in control-plane until we
decide it needs to be put somewhere else.
Change-Id: Ic4924e0041c4cbb955d8fac0f96ec56406d6466e
Some notes on the above:
* "Built-In Control Plane" means the L2 agents, DHCP agents, SGs, metadata
- agents and the portion of ML2 which communicates with the agents.
+ agents and ML2.
* The client includes commands installed server side.
* L3 includes the L3 agent, DVR, and IPAM.
* Services includes FWaaS, LBaaS, and VPNaaS.