Ensure that author preamble has handle or email

[axic]

Fixes #39.

ethereum/EIPs#4560 was merged, so this can be merged too.

[MicahZoltu]

I think we want to allow some authors to have no contact details. Maybe we should rename the field to "editors" (though that is confusing with "EIP editors") to better indicate "these are the people who can automatically make changes" rather than "these are the people involved in authoring this EIP".

[axic]

Maybe we should rename the field to "editors"

I had a discussion about that here: ethereum/EIPs#797

[MicahZoltu]

It would seem that I was even involved in that discussion. If you want to reopen it and change to maintainer you'll have my support. Would require a bit of legwork to update author everywhere and replace it with maintainers everywhere (including bot, website, all historic EIPs), but if someone wants to put in that effort I support the change.