Add access to HTTP request headers in websocket_connection

include/fc/network/http/websocket.hpp

@@ -29,6 +29,8 @@ namespace fc { namespace http {
          void     set_session_data( fc::any d ){ _session_data = std::move(d); }
          fc::any& get_session_data() { return _session_data; }
 
+         virtual std::string get_request_header(const std::string& key) = 0;
+
          fc::signal<void()> closed;
       private:
          fc::any                                   _session_data;

src/network/http/websocket.cpp

@@ -168,6 +168,11 @@ namespace fc { namespace http {
                _ws_connection->close(code,reason);
             }
 
+            virtual std::string get_request_header(const std::string& key)override
+            {
+              return _ws_connection->get_request_header(key);
+            }
+
             T _ws_connection;
       };