fix along the guard rule
fix along the guard rule
fix along the guard file
fix along the guard rule
fix along coding rule
fix along coding rule
Merge branch 'master' into staging
modifired along coding rules
fix along rubocop coding rules
fixed error
Try to fix failures
Merge branch 'master' into torakichi_rubocop
[core/models] Partially satisfy rubocop
Merge branch 'master' into staging

Conflicts:
	core/app/models/gaku/class_group.rb
	core/app/models/gaku/exam_portion.rb
	core/app/models/gaku/grading_method_connector.rb
	core/app/models/gaku/student.rb
	core/app/models/gaku/template.rb
	core/app/models/gaku/user.rb
refactored partially

along the rubocop coding rule in core/app/models
used attr_reader instead of tiny method
refactored partially in core/spec
refactored partially in core/spec