Implement WebSocket client

[armanbilge]

Closes #6.

Tests forthcoming.

[armanbilge]

Ok, this is getting closer. The weirdest issue right now is that the echo web server isn't consistently echoing all the messages. Or at least, they are not being received. Firefox flip-flops between receiving only the first two or all three, whereas Chrome consistently receives only the first one.

[armanbilge]

Update: the problem seems to be the ember websocket echo server I'm running within sbt, since sending to https://echo.websocket.events seems to work perfect. Running an IO within sbt is generally dodgy, of course 😩

[armanbilge]

The problem seems to be with ember server's websocket implementation. Switching to blaze works for now 👍

[armanbilge]

I'm unable to reproduce the problems with Ember server locally. I tried setting the JVM flag -XX:ActiveProcessorCount=1 to more accurately imitate CI but no dice. Maybe just a weird CI thing, idk 🙃

[armanbilge]

Should be good to go. This adds minimal public API, so there's only room for implementation errors 😆