add response settings

example/config.json

@@ -16,6 +16,14 @@
         {
             "host":"127.0.0.1",
             "port":1965
+        },
+        "response":
+        {
+          "default":
+          {
+            "code":20,
+            "meta":"text/gemini; charset=utf-8;"
+          }
         }
     },
     "memcached":

src/server.php

@@ -68,11 +68,11 @@ $server->setHandler(
         $response = new \Yggverse\TitanII\Response();
 
         $response->setCode(
-            20
+            $config->gemini->response->default->code
         );
 
         $response->setMeta(
-            'text/gemini'
+            $config->gemini->response->default->meta
         );
 
         // Route begin