ONOS-1440: Implements port statistics feature, which polls port statistics of all devices every 10 seconds. Also, implemented a simple portstats ONOS CLI command to show the statistics.

Change-Id: I57e046ae2c2463a58b478d3a5b523422cde71ba2
diff --git a/providers/openflow/device/src/test/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProviderTest.java b/providers/openflow/device/src/test/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProviderTest.java
index c83da17..f8b0905 100644
--- a/providers/openflow/device/src/test/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProviderTest.java
+++ b/providers/openflow/device/src/test/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProviderTest.java
@@ -23,6 +23,7 @@
 import static org.onosproject.net.MastershipRole.*;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -41,6 +42,7 @@
 import org.onosproject.net.device.DeviceProviderRegistry;
 import org.onosproject.net.device.DeviceProviderService;
 import org.onosproject.net.device.PortDescription;
+import org.onosproject.net.device.PortStatistics;
 import org.onosproject.net.provider.ProviderId;
 import org.onosproject.openflow.controller.Dpid;
 import org.onosproject.openflow.controller.OpenFlowController;
@@ -217,6 +219,11 @@
                 roles.put(requested, Dpid.dpid(deviceId.uri()));
             }
 
+            @Override
+            public void updatePortStatistics(DeviceId deviceId, Collection<PortStatistics> portStatistics) {
+
+            }
+
         }
     }