Allow package owner to remove themselves

[haacked]

This should only be allowed if you're not the last package owner.
If you're the last package owner, you can simply unlist the package.

[analogrelay]

It sounds like it could be nice, but it's not high enough priority for us to do. Feel free to give us contrary feedback or just send us a PR.

[haacked]

Heh. How dare you ask for a PR. 😛

The simple workaround is to ask another owner to remove you.