title: Rails 3 available_locales excluding gem translations
body: <p>I have a Rails 3 app in which I'm using I18n.available_locales to display a list of available languages for user accounts. In my config/locales directory I only have en and nl yml files, however, I18n.available_locales returns a variety of other locale keys which I'm assuming are present due to translations being present in the gems that I'm using. Is there a common/standard way to get the method to only return the translations present in the app itself?</p>