Found 1 typo + 1 wrong variable.

After a new invitation is made on a resubmission the
reinvited referee will receive an additional mail
to notify him/her about the resubmission and his new invitation.

Also, explicitly added the host to links in the new mail templates
to prevent invalid links.

The url is based off of the DOI. Because the DOI is always the same,
making more than one factory instance crashes the detail page.

UnpublishedVettedCommentaryFactory does not have this problem,
as it has an empty DOI field and a valid (random) arxiv identifier.