use runId for system metrics and corresponding UI changes
Merge branch 'develop' of github.com:caskdata/cdap into feature/system-metrics-use-runId
removed unused code, reduced polling interval, limiting runs returned to 1
Merge pull request #670 from caskdata/feature/system-metrics-use-runId

Feature/system metrics use runId
Spark Integration: Collect system metrics from Spark
Spark Integration: Added support for getting spark metrics from RunTimeStats
Spark Integration: Spark metrics unit test
Fix MetricsRequestParserTest by changing service id to u