Switch from superagent to request

Superagent throws an `unknown compression method` with some urls and it's currently impossible to catch those errors which leads to Shout crashing.  

`plugins/irc-events/link.js`is currently the only plugin that uses any library for creating HTTP-requests so I'd say that at this point it would be easier just to change the HTTP-client we're using. 
https://github.com/visionmedia/superagent/issues/410

Steps to reproduce:
1. Paste this url to any channel: http://www.expert.fi/Tuotteet/Tietokoneet/Naytot/Samsung-U28D590D