CDAP-534 Support Metrics querying by runId

We use the runId of the program for storing metrics along with context and metric name and use runId for querying them as well. We support runId for user metrics and we will make change to support runId with system metrics after the associated UI change.

https://issues.cask.co/browse/CDAP-534
So now runId encapsulates `serviceId`, `runnableId`, `instanceId`, and whatever represents which life of the service it was (e.g. start X, stop X - has runId A, and then starting X again, and stopping X again has runId B)?