security: IMPORTANT CHANGE!! Change Validator constructor to accept Face& instead of shared_ptr<Face>

The old API is kept as deprecated, but will be removed as soon as all
known applications are checked and updated to use new API.

Refs: #1481

Change-Id: Iba0f92b3a3cd48235688f52ab89b2d1f0be9124b
diff --git a/src/security/validator.hpp b/src/security/validator.hpp
index e65d7a8..43ab01a 100644
--- a/src/security/validator.hpp
+++ b/src/security/validator.hpp
@@ -36,10 +36,10 @@
     }
   };
 
-  static const shared_ptr<Face> DEFAULT_FACE;
+  Validator();
 
   explicit
-  Validator(shared_ptr<Face> face = DEFAULT_FACE);
+  Validator(Face& face);
 
   /**
    * @brief Validate Data and call either onValidated or onValidationFailed.
@@ -246,7 +246,8 @@
            int nSteps);
 
 protected:
-  shared_ptr<Face> m_face;
+  bool m_hasFace;
+  Face& m_face;
 };
 
 } // namespace ndn