Anonymize some of our financial data

[choldgraf]

This groups together our income data and also removes the "breakdown by paying community" plot to be less identifiable.

cc @damianavila - what do you think about this?

[damianavila]

Looking quickly at the code, it seems OK.
It would be nice to eventually have some machinery building the PRs because otherwise is quite difficult (without jumping into a local install) to see how the charts will look like.

[choldgraf]

Sounds good - I opened up an issue here to track that one, it's a bit more complex since we use github pages:

• Automate Pull Request previews for this site #7

I'll merge this one in the meantime!