Add support for http(s) proxy

[erdnaxeli]

Hi,

I am trying to deploy the bridge on a restrained environment, where I don't have direct access to Internet. I need the bridge to be able to use an http(s) proxy to talk to discord.

I you have some clues for me I can try to do a PR.

Thanks.

[auscompgeek]

I'm not sure discord.js supports traditional HTTP proxying. You could however reverse proxy Discord, and have the bridge pass the relevant HTTP options when creating a Discord.Client. Your proxy would have to rewrite the /api/vX/gateway response to contain a websocket URI that points to your proxy, I think.

[erdnaxeli]

I actually managed to make it works by running it with proxychains. The websocket works perfectly with an HTTPS proxy.