plugins invitation, invitation-file: adapt service JID and affiliation: if the user part of the service is missing while creating and invitation, it's added because using only the domain will lead to a different repository depending on the requester. In addition, the invitee is added to the repostiroy path as a member, to be sure he/she can access it.

[D-BUS Service]
Name=org.salutatoi.SAT
Exec=sat