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/net/src/main/java/org/onosproject/net/flow/impl/FlowRuleManager.java b/core/net/src/main/java/org/onosproject/net/flow/impl/FlowRuleManager.java
index 94a782a..c3f1200 100644
--- a/core/net/src/main/java/org/onosproject/net/flow/impl/FlowRuleManager.java
+++ b/core/net/src/main/java/org/onosproject/net/flow/impl/FlowRuleManager.java
@@ -122,10 +122,10 @@
     private final FlowRuleDriverProvider defaultProvider = new FlowRuleDriverProvider();
 
     protected ExecutorService deviceInstallers =
-            Executors.newFixedThreadPool(32, groupedThreads("onos/flowservice", "device-installer-%d"));
+            Executors.newFixedThreadPool(32, groupedThreads("onos/flowservice", "device-installer-%d", log));
 
     protected ExecutorService operationsService =
-            Executors.newFixedThreadPool(32, groupedThreads("onos/flowservice", "operations-%d"));
+            Executors.newFixedThreadPool(32, groupedThreads("onos/flowservice", "operations-%d, log"));
 
     private IdGenerator idGenerator;