security: add missing virtual destructor to Validator base class

Change-Id: I4a5aac178c3b61fdb898fdffe67f9271a37e729d
diff --git a/src/security/validator.hpp b/src/security/validator.hpp
index 1f06c83..e6eec8d 100644
--- a/src/security/validator.hpp
+++ b/src/security/validator.hpp
@@ -66,6 +66,9 @@
   explicit
   Validator(Face& face);
 
+  virtual
+  ~Validator();
+
   /**
    * @brief Validate Data and call either onValidated or onValidationFailed.
    *
@@ -213,7 +216,7 @@
               int nSteps,
               const OnDataValidated& onValidated,
               const OnDataValidationFailed& onValidationFailed,
-              std::vector<shared_ptr<ValidationRequest> >& nextSteps) = 0;
+              std::vector<shared_ptr<ValidationRequest>>& nextSteps) = 0;
 
   /**
    * @brief Check the Interest against validation policy and return the next validation step
@@ -233,7 +236,7 @@
               int nSteps,
               const OnInterestValidated& onValidated,
               const OnInterestValidationFailed& onValidationFailed,
-              std::vector<shared_ptr<ValidationRequest> >& nextSteps) = 0;
+              std::vector<shared_ptr<ValidationRequest>>& nextSteps) = 0;
 
   typedef function<void(const std::string&)> OnFailure;
 
@@ -320,7 +323,7 @@
    * @param onFailure Failure callback when errors happen in processing nextSteps.
    */
   virtual void
-  afterCheckPolicy(const std::vector<shared_ptr<ValidationRequest> >& nextSteps,
+  afterCheckPolicy(const std::vector<shared_ptr<ValidationRequest>>& nextSteps,
                    const OnFailure& onFailure);
 
 protected: