When banning a user, remove communities they've created

[dessalines]

• Fixes Have user ban post and comment deletion also remove communities where they're the top mod. #1659

[dessalines]

I tested to verify it works correctly.

[Nutomic]

Nice. Looks like this only happens when "Remove Posts and Comments" is checked, so we need to change that string.

[dessalines]

I spose, remove content, would work?

[Nutomic]

Yes but there should be a more detailed explanation (eg as mouseover, or a link to docs).