Add the WTFPL as our licence

I'm in favour of the WTFPL as it's nice and simple, but I'd understand if someone preferred something like MIT. I'd rather not use the GPL because that discourages contribution and makes it harder to link against some things.

There's also the issue that HackSoc isn't a legal entity, and so I'm not sure exactly to whom the software is licensed. The developers? Me? Each bit of code belonging to whoever wrote it?