Further refactor of QuestionsController

Use before actions for finding or building models
Use barewords (methods) for isolating access to instance variables
Prefer data over code. For example let ActiveRecord handle associating lessons
to questions using lesson_id rather than associating them by code.
Merge branch 'master' into develop
Fix returning one lesson
Refactor quiz controller
Further refactor of QuestionsController

Use before actions for finding or building models
Use barewords (methods) for isolating access to instance variables
Prefer data over code. For example let ActiveRecord handle associating lessons
to questions using lesson_id rather than associating them by code.
Add SideKiq
sample worker
Merge branch 'develop' of https://github.com/psamim/darsnameh into develop

* 'develop' of https://github.com/psamim/darsnameh:
  Add SideKiq
  Refactor quiz controller
  Fix returning one lesson
  Merge branch 'master' into develop
  Further refactor of QuestionsController

Conflicts:
	Gemfile.lock
Add duration_days to lessons
Add sidekiq workers, Modify mailer and controller
Comment jazz-hands gem
Refactor courses model, controller and views
Refactor lessons model, controllers and views
Refactor questions model, controllers and views
Add validation, remove timestamp for answers
Merge branch 'develop'
Create model enrollment
Make quiz show view nicer