Add OpenUpgrade specific functions for message_last_post fields

Add set_message_last_post() which fills message_last_post values

Signed-off-by: Sandy Carter <sandy.carter@savoirfairelinux.com>
Add documentation of OpenUpgrade 8.0 specific API

Signed-off-by: Sandy Carter <sandy.carter@savoirfairelinux.com>
Init of analysis work file for mail

Signed-off-by: Sandy Carter <sandy.carter@savoirfairelinux.com>
Add pre and post migration scripts for mail

Migrate selections for notifications to new selection options
Move 'server_id' and 'reply_to' from mail.mail to mail.message

Signed-off-by: Sandy Carter <sandy.carter@savoirfairelinux.com>