BGP router now handles the case where groups don't exists right away.

Also reworked some logic to make delete routes work.

Change-Id: I1f65279284b85144a847f1295fcbd7695cb59167
diff --git a/apps/bgprouter/src/main/java/org/onosproject/bgprouter/NextHopGroupKey.java b/apps/bgprouter/src/main/java/org/onosproject/bgprouter/NextHopGroupKey.java
index 5193f4b..ae281e3 100644
--- a/apps/bgprouter/src/main/java/org/onosproject/bgprouter/NextHopGroupKey.java
+++ b/apps/bgprouter/src/main/java/org/onosproject/bgprouter/NextHopGroupKey.java
@@ -24,16 +24,26 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 
 /**
- * Created by jono on 2/16/15.
+ * Identifier for a next hop group.
  */
 public class NextHopGroupKey implements GroupKey {
 
     private final IpAddress address;
 
+    /**
+     * Creates a new next hop group key.
+     *
+     * @param address next hop's IP address
+     */
     public NextHopGroupKey(IpAddress address) {
         this.address = checkNotNull(address);
     }
 
+    /**
+     * Returns the next hop's IP address.
+     *
+     * @return next hop's IP address
+     */
     public IpAddress address() {
         return address;
     }