Export facet values and duration dates

Exposes facet and scheme duration data in the business support scheme CSV export
https://www.pivotaltracker.com/story/show/73962054
This will run into problems if more than one fact type have a facet with a common slug.  There's nothing that enforces that slugs must be unique across all the different types.

Also, the indentation is a little odd here.  Private methods shouldn't be indented differently to public methods.