Upgrade factory_girl_rails to 4.5.0
Update Gemfile
Upgrade to new FactoryGirl syntax

Conflicts:

	spec/controllers/courses_controller_spec.rb
Documentation improvements
Merge branch 'rspec-3' into factory-girl-4
Update Changelog.md
Merge branch 'rspec-3' into rails-4
Merge branch 'factory-girl-4' into rails-4

Conflicts:
	Changelog.md
	spec/lib/exercise_completion_status_generator_spec.rb
Code style