74977456 'Articles model/controller/view specs refactoring'

https://www.pivotaltracker.com/story/show/74977456
(part of epic 74977456 https://www.pivotaltracker.com/epic/show/1288994)
opted for FactoryGirl.build
reason: build_stubbed is incompatible with the POST :create used in this example because build_stubbed objects are not allowed to interact with the database. build is permitted however.