add stomp.js 2.3.1

stomp.js is a JavaScript library to send and receive STOMP messages over
Web Sockets and is supported by all major Open Source messaging brokers
(ActiveMQ, RabbitMQ, HornetQ).

Homepage: https://github.com/jmesnil/stomp-websocket
Version downloads: https://github.com/jmesnil/stomp-websocket/releases/tag/2.3.1