(PDB-772) Modify the facts endpoint to return structured facts

This pull request causes the v4 facts endpoint to return typed and structured
facts while leaving the v3 responses stringified as before.  It also adds a
"name" column to the fact_paths table representing the first element of a
fact's path.  This column should be renamed to "fact" in the future to avoid
confusion with the many references to 'certname' as name.
Actually come to think of it, I do have 1 concern. What happens when someone uses our pagination feature, and orders by something other than name or certname? Does this break stuff badly? Can we confirm perhaps?