this conversation was carried out over email. from my response:

Wagn does not currently have a free hosting service (it costs about $5 per month at Cloudstore), which may in itself eliminate it from your search. You do have full access to a complete database dump and can also export it as json. There is no import set up to handle plain text files, but scripting one would not be difficult for a ruby programmer.

I'm not exactly sure of a service that meets your needs, but the one that comes to mind first is SFW (the Smallest Federated Wiki).