Merge pull request Netflix#49 from jeffastorey/1.x

using daemon threads for the InstanceMonitor for cleaner shutdown

turbine-core/src/main/java/com/netflix/turbine/monitor/instance/InstanceMonitor.java

@@ -111,6 +111,7 @@ public class InstanceMonitor extends TurbineDataMonitor<DataFromSingleInstance>
 
         public Thread newThread(Runnable r) {
             Thread thread = defaultFactory.newThread(r);
+            thread.setDaemon(true);
             thread.setName(ThreadName);
             return thread;
         }