Simplify the DocumentsController tests.
Simplify the DocumentsController tests.

This make more sense now that we've extracted Document#published_edition.

hotvulcan/whitehall,hotvulcan/whitehall,YOTOV-LIMITED/whitehall,hotvulcan/whitehall,ggoral/whitehall,YOTOV-LIMITED/whitehall,ggoral/whitehall,hotvulcan/whitehall,alphagov/whitehall,alphagov/whitehall,askl56/whitehall,askl56/whitehall,YOTOV-LIMITED/whitehall,YOTOV-LIMITED/whitehall,robinwhittleton/whitehall,askl56/whitehall,alphagov/whitehall,robinwhittleton/whitehall,robinwhittleton/whitehall,ggoral/whitehall,alphagov/whitehall,ggoral/whitehall,askl56/whitehall,robinwhittleton/whitehall