Added a function to get a UniqueName's ID

This fixes #431

Signed-off-by: Cruz Julian Bishop <cruzjbishop@gmail.com>

common/src/main/java/io/netty/util/UniqueName.java

@@ -55,6 +55,10 @@ public class UniqueName implements Comparable<UniqueName> {
         return name;
     }
 
+    public final int id() {
+        return id;
+    }
+
     @Override
     public final int hashCode() {
         return super.hashCode();