Querki needs to deal with the EU Safe Harbor problem

(User Story, Investigate , Priority: High, Test Status: No automated tests yet , Reported By Justin du Coeur, )
System
Summary: This will take a lot of time, architecture and thought. As of October 2015, the EU/US Safe Harbor agreement has been struck down. This means that Querki needs to be careful about not transferring personal data on EU citizens to the US.
Lots of research needed here.
First of all, what is the definition of personal data? In particular, is this just data about the user, or does it include that user's Spaces?
Odds are fairly good that we will need to lease server space in Europe somewhere in the medium term, and use that part of the WAN to hold all user data for the Europeans. But if those user's Spaces are included as well, we have a bigger problem: how do we avoid balkanizing Querki along geographical lines? Is it possible to avoid such balkanization?