TrafficMap API in SMI Metrics

[Pothulapati]

Part of #71

There is a real interest in smi-metrics directly having an end-point where a service graph is returned. The discussion around this can be done here

Initial Questions

• What should the response graph format be?
• What should be the metrics that should be present at the edges level?
• What should the granularity of the graph should be? service level, pod level. How should we submit multiple levels?

Feel free add questions/suggestions in the comments. @michelleN