Use erb for admin menu
[locale] for import file
Merge pull request #322 from Genshin/locales_for_imex

[locale] for import file
[locale] notice for import action
[controller] redirect_to login
Merge pull request #323 from Genshin/locale_for_import_action

[locale] notice for import action
Merge pull request #324 from Genshin/redirect_to_login

[controller] redirect_to login
[spec/controller] fix no user logged
Merge pull request #326 from Genshin/fix_student_controller_spec

[spec/controller] fix no user logged
Merge branch 'master' into implement_other_grading_methods