You first add the dependency to your project :
bower install i18next --save
Then, if you store your translations in the default path (/locales/en/translations.json and so on) then add the following to the Gruntfile.j copy:dist definition :
copy: { dist: { files: [{ expand: true, dot: true, cwd: '<%= yeoman.app %>', dest: '<%= yeoman.dist %>', src: [ '*.{ico,png,txt}', '.htaccess', 'bower_components/**/*', 'images/{,*/}*.{gif,webp}', 'fonts/*', 'locales/**/*' ] }