Deserialization of query results through the ExploreClient better supports the different types
Addressed PR comments
(CDAP-656) Set Context ClassLoader to program ClassLoader for user Service.
Merge pull request #580 from caskdata/feature/explore-results-deserialization

Better deserialization of query results through the ExploreClient
Spark Integration: SparkPageRank now uses Service
Merge pull request #622 from caskdata/feature/sparkpr-service

Spark Integration: SparkPageRank now uses Service
Merge pull request #640 from caskdata/feature/service-context-classloader

(CDAP-656) Set Context ClassLoader to program ClassLoader for user Service
Remove hardcoded b from MapReduce metrics context
Merge pull request #642 from caskdata/feature/mr-metric-fix

Remove hardcoded b from MapReduce metrics context
Merge remote-tracking branch 'upstream/develop' into CDAP-538-purchase-app
CDAP-538: Updated response when history not found; Updated tests to waiting service startup.
CDAP-538: Updated docs of PurchaseHistoryService.