Add medium post links to fetchall.py

[amiller]

I am starting to work on adding more blog post content. It looks like so far all the post links are scraped from hacking distributed. So far when my students want to post something they have found medium to be the most convenient interface. E.g., this post on fake stake attacks I wished would have shown up on ic3 blog at the time
https://medium.com/@dsl_uiuc/fake-stake-attacks-on-chain-based-proof-of-stake-cryptocurrencies-b8b05723f806
I have another one to add this week as well. So my proposal is to extend ic3-website/fetchall.py with an additional functions to parse medium posts, to add dsl_uiuc as one, and then assuming other IC3 faculty use a similar system for blogging, to add posts one link at a time or by their name like that