add spec to user category video
improve coding sytle in controllers
refactoring controllers and models spec
testing request user in video controller
controller test in sessions and users: signin/out
Merge branch 'master' of https://github.com/jccf091/myflix

Conflicts:
	Gemfile
	Gemfile.lock
	app/controllers/users_controller.rb
	app/controllers/videos_controller.rb
	app/helpers/sessions_helper.rb
	app/models/user.rb
	spec/controllers/categories_controller_spec.rb
	spec/controllers/users_controller_spec.rb
	spec/controllers/videos_controller_spec.rb
	spec/models/category_spec.rb
	spec/models/user_spec.rb
	spec/models/video_spec.rb
	spec/spec_helper.rb