Add example of extending a nested class

Author: mythz

src/AndroidClient/android/src/androidTest/java/net/servicestack/android/ExtendedRockstar.java

@@ -0,0 +1,13 @@
+package net.servicestack.android;
+
+/**
+ * Created by mythz on 6/30/2015.
+ */
+public class ExtendedRockstar extends dto.Rockstar {
+    public Integer ExtendedId = null;
+
+    public ExtendedRockstar(Integer extendedId) {
+        ExtendedId = extendedId;
+        super.Id = extendedId;
+    }
+}