Force the path to be treated as UTF-8
Fix error resolving relation parents

It's not entirely clear why specifying the foreign key explicitly
fixes this - the value given is what it should default to - but
without this it finds the child relation instead when looking at
the parents of a relation.

Fixes #789
Merge branch 'master' of github.com:openstreetmap/openstreetmap-website into wikidata-links