Refactor static pages controller specs

Refactored the expressions so they could fit the recommended rspec3 syntax, as well: 
- added :type => : controller
- build_stubbed the user
- preserved the create statements for the page and child page, because of their relationship and the many methods stubs that had to be done
- added 'expect' in the places where 'should' was used

PT Link: https://www.pivotaltracker.com/story/show/76941170
allow(request.env['warden']).to receive(:authenticate).and_return(user)