Intervention goal creators are determined from dublin core creator list

[Justas Sadzevičius]

I'd discourage use of dublincore for determining the sender for a lot of reasons, mainly:
- dublin.creators[0].split('.')[2] is not that much readable.
- it is also not reliable: users can get deleted, renamed, etc.

(and I think dublin core is evil in general)

Please use schooltool.relationship to specify the owner of the goal.

Note you will need evolution script also.