[fix&refactor] extended search;change achievemnt to badge type
[views] student achievement to badge
[controller] student achievements to badges
[spec/controller] student achievement to badges
[spec/feature] student achievement to badges
[model] change student association with badges
[spec/routes] student achievement to badges
[decorator] refator to use badges
[routes] badges
[locale] badges
[spec/model] students/badges assoc
[sample] badges