message: Add ErrorHandler virtual destructor
  Virtual destructor added to the ErrorHandler since derived class
  destructor should be called when destroying an object via a pointer to
  the base type (ErrorHandler in this case).
diff: @@ -41,6 +41,10 @@ public:
  */
  typedef web::protocol::http::Headers Headers;
  public:
  + /**
  + * Virtual destructor since the class is ment to be derived from.
  + * */
  + virtual ~ErrorHandler() = default;
  /**
  * Implement this method!
  