We remove 'secret' field, as it won't be of use in interactions
between la Régie and dimail. Régie credentials will be stored and used
as project variable.
We previously accepted '+' as a special caracter during mailbox creation.
We now remove it, as this caracter has a very special meaning and it wouldn't
make sense to create a mail using it.
We want people to create new mailboxes in La Régie.
This commit adds integration with intermediary dimail-api,
which will in turn send our email creation request to Open-Xchange.
Rename member role to viewer role for MailDomainAccess.
A viewer is only allowed to see list of mailboxes
created for a domain. It makes more sense to name it viewer.
