Remove host location when port down or device down

Also refactor Host Location Provider

Change-Id: I57d682ee51e80ddd7e141883521a12da705a336d
diff --git a/providers/netcfghost/src/test/java/org/onosproject/provider/netcfghost/NetworkConfigHostProviderTest.java b/providers/netcfghost/src/test/java/org/onosproject/provider/netcfghost/NetworkConfigHostProviderTest.java
index ac47dba..50071db 100644
--- a/providers/netcfghost/src/test/java/org/onosproject/provider/netcfghost/NetworkConfigHostProviderTest.java
+++ b/providers/netcfghost/src/test/java/org/onosproject/provider/netcfghost/NetworkConfigHostProviderTest.java
@@ -121,7 +121,12 @@
 
         @Override
         public void removeIpFromHost(HostId hostId, IpAddress ipAddress) {
-            // Note: This method is never used.
+
+        }
+
+        @Override
+        public void removeLocationFromHost(HostId hostId, HostLocation location) {
+
         }
 
         public void clear() {