Change mock for concepts-31-fields.json
Change mock for concepts-31-fields.json

The vocab browser uses _link.self to refer to its own resource root,
so here self.href needs to point to a new root.json file for the
vocab browser. Originally I used values for this, but it really didn't
seem to make sense the more I worked with it

chop-dbhi/cilantro,chop-dbhi/cilantro,chop-dbhi/cilantro