Bumps node version to 18, introduces standard.

Author: 4name

README.md

@@ -2,6 +2,7 @@
 [![Coverage Status](https://img.shields.io/coveralls/diversario/node-ssdp.svg)](https://coveralls.io/r/diversario/node-ssdp?branch=master)
 [![Dependency Status](https://gemnasium.com/diversario/node-ssdp.png)](https://gemnasium.com/diversario/node-ssdp)
 [![NPM version](https://badge.fury.io/js/node-ssdp.svg)](http://badge.fury.io/js/node-ssdp)
+[![js-semistandard-style](https://img.shields.io/badge/code%20style-semistandard-brightgreen.svg)](https://github.com/standard/semistandard)
 
 ## Installation