CORD-613 Adding ability to administratively enable or disable a port via CLI.
Currently uses the OpenFlow device provider to change portState.
Also fixes a bug in PortNumberCompleter.
Adds completion options to portstats for deviceId and portNumber.

Change-Id: Idcce775fe8bc5484fdd0e630bcb5026b85125478
diff --git a/core/api/src/main/java/org/onosproject/net/device/DeviceProvider.java b/core/api/src/main/java/org/onosproject/net/device/DeviceProvider.java
index d8adbb0..1727fc8 100644
--- a/core/api/src/main/java/org/onosproject/net/device/DeviceProvider.java
+++ b/core/api/src/main/java/org/onosproject/net/device/DeviceProvider.java
@@ -17,6 +17,7 @@
 
 import org.onosproject.net.DeviceId;
 import org.onosproject.net.MastershipRole;
+import org.onosproject.net.PortNumber;
 import org.onosproject.net.provider.Provider;
 
 /**
@@ -54,4 +55,14 @@
      * @return true if reachable, false otherwise
      */
     boolean isReachable(DeviceId deviceId);
+
+    /**
+     * Administratively enables or disables a port.
+     *
+     * @param deviceId device identifier
+     * @param portNumber device identifier
+     * @param enable true if port is to be enabled, false to disable
+     */
+    void changePortState(DeviceId deviceId, PortNumber portNumber,
+                         boolean enable);
 }