add new log for stop agent

add new log for stop agent

Bench4Q-Master/src/main/java/org/bench4q/master/domain/entity/TestPlanScript.java

@@ -272,6 +272,8 @@ public class TestPlanScript extends Observable implements
 			StopTestModel resultModel = this.getAgentMessenger().stop(
 					runningAgent.getAgent(), runningAgent.getAgentRunId());
 			if (resultModel == null || !resultModel.isSuccess()) {
+				logger.error("can't stop the agent with hostName"
+						+ runningAgent.getAgent().getHostName());
 				doFaultTolerance(runningAgent);
 				continue;
 			}