api: Major API change.  OnInterest/OnData callbacks now use just references, not shared pointers

If shared pointer is necessary, it can be obtained using
.shared_from_this() on Interest or Data object.

This commit also corrects all internal uses of expressInterest/setIntersetFilter.

Change-Id: I20207a5789fd189902f2c6e3827260b6b27a2514
diff --git a/src/security/validator-null.hpp b/src/security/validator-null.hpp
index 27dc63d..d1d8faa 100644
--- a/src/security/validator-null.hpp
+++ b/src/security/validator-null.hpp
@@ -21,20 +21,20 @@
   
 protected:
   virtual void
-  checkPolicy (const shared_ptr<const Data>& data, 
+  checkPolicy (const Data& data, 
                int stepCount, 
                const OnDataValidated &onValidated, 
                const OnDataValidationFailed &onValidationFailed,
                std::vector<shared_ptr<ValidationRequest> > &nextSteps)
-  { onValidated(data); }
+  { onValidated(data.shared_from_this()); }
   
   virtual void
-  checkPolicy (const shared_ptr<const Interest>& interest, 
+  checkPolicy (const Interest& interest, 
                int stepCount, 
                const OnInterestValidated &onValidated, 
                const OnInterestValidationFailed &onValidationFailed,
                std::vector<shared_ptr<ValidationRequest> > &nextSteps)
-  { onValidated(interest); }
+  { onValidated(interest.shared_from_this()); }
 };
 
 }