Allow authors without email addresses

[ajrbyers]

Sometimes when loading back content users will not know an authors email address. We should make this optional and generate an @journal.com address when its empty.

[mauromsl]

There is an interplay of @journal.com and the new boolean to control display of email addresses. Currently (janeway v1.5+) when adding an author with a DUMMY_EMAIL_ADDRESS domain, it will still be displayed by default unless one goes to the edit metadata page and toggles display email link off.

For this issue, on top of allowing blank email address, we should also add the toggle for display email link