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/tests/test-validator.cpp b/tests/test-validator.cpp
index 1b24a3d..19e2b78 100644
--- a/tests/test-validator.cpp
+++ b/tests/test-validator.cpp
@@ -38,8 +38,9 @@
   keyChain.signByIdentity(*data, identity);
   
   ValidatorNull validator;
-  
-  validator.validate(data,
+
+  // data must be a shared pointer
+  validator.validate(*data,
 		     bind(&onValidated, _1),
 		     bind(&onValidationFailed, _1));