Improve the email sent to invite a user to approve/sign/assist/view a
document.
The current links "Reject Document" / "Sign Document" confuse some users
as they think the document will be rejected/signed just by clicking on
these buttons.
This change makes it more clear that they will have a chance to view the
document before they can reject/sign.
When sending a document for signing, emails for recipients are sent
before the document status is updated.
In this case, the job "send.signing.requested.email" fails because it
cannot find the document with a PENDING status.
samuel-cglg