Feature/json exporter

A quick first pass at a JSON exporter. Would welcome some feedback around which fields are required, useful, etc.

For #5343

Note that this hasn't touched the XML export functionality at all.
I'll double check that. 

I figured it was safe because it's one profile through a person, and we're deleting the person (why have an orphan profile?), but I'll check the existing functionality to see that it matches.