Allow users to delete keys?

• Users should be able to delete their own old key, if they're providing a new one.

• Users shouldn't be allowed to delete keys of others.

• But users could assign others key to their own subscription and after this, delete the key.

• Therefore we can't allow that.

• Idea: We can't verify GPG signature via the web. Users should be able to click mailto link to send a mail to schleuder to delete their key.