Adding a component config to take down single homed host ports when all uplinks are lost.

In addition:
   - handle port updates that may be lost if mastership changes at same time
   - fix javadoc in DeviceService

Change-Id: I032909e8ab9564cf9c978b1d66abd3ab32c814d7
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 f86a98a..86d9025 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
@@ -187,11 +187,11 @@
 
 
     /**
-     * Indicates how long ago the device connected or disconnected from this
-     * controller instance as a time offset.
+     * Indicates the time at which the given device connected or disconnected
+     * from this controller instance.
      *
      * @param deviceId device identifier
-     * @return time offset in miliseconds
+     * @return time offset in miliseconds from Epoch
      */
     long getLastUpdatedInstant(DeviceId deviceId);