Update service API to better handle logging.
Update service API to better handle logging.

This adds logging levels to ExecTask so clients can control the level of logging in
the services.

Change-Id: I72744b3f46b1d9cf1a091553143bb53af1dc41f2
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/6880
Tested-by: jenkins
Reviewed-by: Nong Li <99a5e5f8f5911755b88e0b536d46aafa102bed41@cloudera.com>

cloudera/RecordServiceClient,cloudera/RecordServiceClient,cloudera/RecordServiceClient,cloudera/RecordServiceClient,cloudera/RecordServiceClient