Ideas for egress traffic shaping

[wangxf1987]

Description

Contiv can be set the ingress rate limit and use the openvswitch port, that openvswitch have the
implement for ports.
However, some specical applications need to implement egress traffic shaping.

Expected Behavior

1. modify the CreatePort method in the ovsdbDriver.go
2. Add a actual para for egress.
3. check the para, if not none, that create queue for the special interface.
4. return d.performOvsdbOps(operations)
5. it's may be need to modify delete port method.

Observed Behavior

1. use the policing do the traffic rate limit.
2. use the queue of shaping do the egress traffic shaping.

Steps to Reproduce (for bugs)

1. modify the CreatePort method in the ovsdbDriver.go
2. Add a actual para for egress.
3. check the para, if not none, that create queue for the special interface.
4. return d.performOvsdbOps(operations)
5. it's may be need to modify delete port method.

Your Environment

contiv latest version