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
Those two runs of flowlet will have different run-Id, as run-Id uniquely identifies a program run, so we should be able to get those separate metrics if passed the runId in query, but if we want to add another group id to query by , then we need to have those in place before adding support in metrics right ? please clarify