Site::all fails if the last page from the API has exactly one site in it

If the SE API returns exactly one site on the last page of the 'sites' call, make_request in request.rb returns that item instead of the entire result. This causes problems when all_helper in relation.rb attempts to access has_more, because it doesn't exist.

Proposed solution: before kicking off the response, set @qty to :plural to force Request to return the entire result.