Document filtering feature
Add FacetCollection
Fixup FacetCollection spec
Facet initialises from a schema and takes a value
Add SelectFacet

also add an after_initialize hook to facet
Add factory build method to Finder
Flesh out finders controller
Render facet collections
Flesh out filtering feature steps
Use modified version of gds-api-adapters -- WIP
Add Document, ResultSet and Finder#results
Render search results
Change port for startup script
Remove CMAFinder
First pass of document filtering