Improve Executors related logging behavior

- Specify Logger for the Executor
- Use Executor#execute instead of ExecutorService#submit for
  fire and forget type of usage.
   Note: submit() will swallow thrown Exception

Change-Id: I507b841dc3feedf4ad20a746c304518d68fb846a
diff --git a/core/store/dist/src/main/java/org/onosproject/store/device/impl/GossipDeviceStore.java b/core/store/dist/src/main/java/org/onosproject/store/device/impl/GossipDeviceStore.java
index a10b79d..e5f40b3 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/device/impl/GossipDeviceStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/device/impl/GossipDeviceStore.java
@@ -96,13 +96,13 @@
 import java.util.Set;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Predicates.notNull;
 import static com.google.common.base.Verify.verify;
+import static java.util.concurrent.Executors.newCachedThreadPool;
 import static java.util.concurrent.Executors.newSingleThreadScheduledExecutor;
 import static org.apache.commons.lang3.concurrent.ConcurrentUtils.createIfAbsentUnchecked;
 import static org.onlab.util.Tools.groupedThreads;
@@ -200,10 +200,10 @@
 
     @Activate
     public void activate() {
-        executor = Executors.newCachedThreadPool(groupedThreads("onos/device", "fg-%d"));
+        executor = newCachedThreadPool(groupedThreads("onos/device", "fg-%d", log));
 
         backgroundExecutor =
-                newSingleThreadScheduledExecutor(minPriority(groupedThreads("onos/device", "bg-%d")));
+                newSingleThreadScheduledExecutor(minPriority(groupedThreads("onos/device", "bg-%d", log)));
 
         clusterCommunicator.addSubscriber(
                 GossipDeviceStoreMessageSubjects.DEVICE_UPDATE, new InternalDeviceEventListener(), executor);