Fixed a number of CLI commands.
Refactored the StoreService/Manager stuff for common serializer pool.
diff --git a/cli/src/main/java/org/onlab/onos/cli/net/ClusterDevicesCommand.java b/cli/src/main/java/org/onlab/onos/cli/net/ClusterDevicesCommand.java
index a6f3048..f0217de 100644
--- a/cli/src/main/java/org/onlab/onos/cli/net/ClusterDevicesCommand.java
+++ b/cli/src/main/java/org/onlab/onos/cli/net/ClusterDevicesCommand.java
@@ -31,7 +31,7 @@
     };
 
     @Override
-    protected Object doExecute() throws Exception {
+    protected void execute() {
         int cid = Integer.parseInt(id);
         init();
         TopologyCluster cluster = service.getCluster(topology, clusterId(cid));
@@ -44,8 +44,6 @@
                 print("%s", deviceId);
             }
         }
-
-        return null;
     }