MINOR: http: Add 410 to http-request deny

This patch adds http status code 410 Gone to http-request deny. See
issue #80.
diff --git a/include/common/http.h b/include/common/http.h
index 857c66e..2d9bad7 100644
--- a/include/common/http.h
+++ b/include/common/http.h
@@ -85,6 +85,7 @@
 	HTTP_ERR_403,
 	HTTP_ERR_405,
 	HTTP_ERR_408,
+	HTTP_ERR_410,
 	HTTP_ERR_421,
 	HTTP_ERR_425,
 	HTTP_ERR_429,