ndns-dig: adapt to the fact that NDN testbed does not have root zone

- Enable dig to set the start label during iterative process.
- Enable validation of intermediate results with an option to disable
it

Change-Id: I221e3c328c875ad06a1f8094f1004e68d9d46a57
diff --git a/src/clients/query-controller.hpp b/src/clients/query-controller.hpp
index 778d563..7729ea2 100644
--- a/src/clients/query-controller.hpp
+++ b/src/clients/query-controller.hpp
@@ -68,6 +68,9 @@
   virtual bool
   hasEnded() = 0;
 
+  virtual void
+  setStartComponentIndex(size_t startIndex) = 0;
+
 public:
   ////////////////
   // getter