Add uptimes to device and cluster REST APIs

Change-Id: I0ccdf4e33135be4bcfd1674a76ff4b39e992268b
diff --git a/core/api/src/main/java/org/onosproject/net/device/DeviceService.java b/core/api/src/main/java/org/onosproject/net/device/DeviceService.java
index 232809b..f86a98a 100644
--- a/core/api/src/main/java/org/onosproject/net/device/DeviceService.java
+++ b/core/api/src/main/java/org/onosproject/net/device/DeviceService.java
@@ -185,4 +185,14 @@
      */
     String localStatus(DeviceId deviceId);
 
+
+    /**
+     * Indicates how long ago the device connected or disconnected from this
+     * controller instance as a time offset.
+     *
+     * @param deviceId device identifier
+     * @return time offset in miliseconds
+     */
+    long getLastUpdatedInstant(DeviceId deviceId);
+
 }
diff --git a/core/api/src/main/java/org/onosproject/net/device/DeviceServiceAdapter.java b/core/api/src/main/java/org/onosproject/net/device/DeviceServiceAdapter.java
index 125cbcc..f85d198 100644
--- a/core/api/src/main/java/org/onosproject/net/device/DeviceServiceAdapter.java
+++ b/core/api/src/main/java/org/onosproject/net/device/DeviceServiceAdapter.java
@@ -142,4 +142,9 @@
         return null;
     }
 
+    @Override
+    public long getLastUpdatedInstant(DeviceId deviceId) {
+        return 0;
+    }
+
 }
diff --git a/core/api/src/main/java/org/onosproject/net/utils/ForwardingDeviceService.java b/core/api/src/main/java/org/onosproject/net/utils/ForwardingDeviceService.java
index acca07f..3a3eea2 100644
--- a/core/api/src/main/java/org/onosproject/net/utils/ForwardingDeviceService.java
+++ b/core/api/src/main/java/org/onosproject/net/utils/ForwardingDeviceService.java
@@ -127,4 +127,9 @@
         return delegate.localStatus(deviceId);
     }
 
+    @Override
+    public long getLastUpdatedInstant(DeviceId deviceId) {
+        return delegate.getLastUpdatedInstant(deviceId);
+    }
+
 }