Add ergonlogic as a maintainer

Hi @joestewart,

I got these Behat/Mink tests (mostly) running on the 7.x-3.x branches of Aegir. I'll be working on some definitions to check that tasks run successfully, and that task logs don't contain any errors. I'd like to be able to commit them back here in a 7.x-3.x branch, if you're open to that.