Migrate Sponsor Information

[flowirtz]

https://hackhpi.org/sponsor-information/

seems this was lost during migration

[jkbe]

Make sure to remove contents of the page for the 2018 version of sponsor-information.html in line with #20.

[jkbe]

Is this necessarily part of the release milestone in your opinion, @fwirtz?

[flowirtz]

@jak-ing yes, because otherwise it's gone for good. We at least need to migrate the text from the last years.