IPFS support for file uploads

[Mikaela]

It would be nice if TeleIRC could put all file uploads to local IPFS node and give IRC a link to a gateway. It would accidentally also resolve #238 thanks to deduplicating and if multiple TeleIRC instances were using IPFS and uploaded the same files/stickers, IPFS would happily fetch the content from them all.

• https://ipfs.io/

As a drawback I think this would complicate managing files by hand such as if someone accidentally uploaded something sensitive and there would be a method within TeleIRC to unpin/remove old files or all files it has put to IPFS and a time limit how old files to store would also be nice.