Fix #299

Author: yhirose

httplib.h

@@ -1561,6 +1561,7 @@ inline const char *find_content_type(const std::string &path) {
 inline const char *status_message(int status) {
   switch (status) {
   case 200: return "OK";
+  case 204: return "No Content";
   case 206: return "Partial Content";
   case 301: return "Moved Permanently";
   case 302: return "Found";