http write returns success on connection close (API Change):

fix #767

The write family of HTTP stream algorithms no longer returns
error::end_of_stream when the message indicates that the connection
should be closed.

Actions Required:

* Add code to servers to close the connection after successfully
  writing a message where `message::keep_alive()` would return `false`.

example/http/server/small/http_server_small.cpp

@@ -100,8 +100,8 @@ private:
     void
     process_request()
     {
-        response_.version(11);
-        response_.set(http::field::connection, "close");
+        response_.version(request_.version());
+        response_.keep_alive(false);
 
         switch(request_.method())
         {