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/DeviceRoleCommand.java b/cli/src/main/java/org/onlab/onos/cli/net/DeviceRoleCommand.java
index 32da169..ddccdaf 100644
--- a/cli/src/main/java/org/onlab/onos/cli/net/DeviceRoleCommand.java
+++ b/cli/src/main/java/org/onlab/onos/cli/net/DeviceRoleCommand.java
@@ -23,11 +23,10 @@
     String role = null;
 
     @Override
-    protected Object doExecute() throws Exception {
+    protected void execute() {
         MastershipRole mastershipRole = MastershipRole.valueOf(role.toUpperCase());
         getService(DeviceAdminService.class).setRole(DeviceId.deviceId(uri),
                                                      mastershipRole);
-        return null;
     }
 
 }