[migration] students has many achievements throught student achievements
[model] student and achivement  has_many :through join model
[achievement] basic controller & routes
[admin] admin achievement crud
[migration] add assertion to student achievements join model
[menu] add achievements to admin global menu
fix image_resize helper variables name
Merge remote-tracking branch 'tapalilov/develop' into develop
updated locales
forgot to add some translations
mini fix