Migration format 0.3

proposal
There are no multitenants application in the migration format. For mail, this is an application we offer to our user. This apllication is called "mail-forwarding" and the migration format is a text file with the definition of the forwards. The runme could even be our docker file. Then people are free to provide the service the way they want.
And for haproxy, it makes even less sense. This is really specific to our implementation. This is the way we run the migration format, but people should be free to do as they want.