Updating django-knowledge for Django 2.0.1

[ktryber]

Hello Zapier,

I'm a pretty new developer, I'm currently building a point of sale system for my company that i've built with django. I wanted to also integrate a knowledge base for all of the processes that we've written. This project had the nuts and bolts of what I wanted so I installed it into my project and updated everything to get it working. While doing that I thought I'd contribute to my first ever project on github. I know that you guys don't maintain this anymore so I'm not sure if you guys will see this but it's worth a shot. Any feedback would be great and I apologize for any commit messages that aren't very clear. You can tell that I work alone most of the time.