Merge pull request #406 from jhawthorn/optimize_available_locales

Optimize Backend::Simple#available_locales

Author: radar

lib/i18n/backend/simple.rb

@@ -44,7 +44,7 @@ def store_translations(locale, data, options = {})
         def available_locales
           init_translations unless initialized?
           translations.inject([]) do |locales, (locale, data)|
-            locales << locale unless (data.keys - [:i18n]).empty?
+            locales << locale unless data.size <= 1 && (data.empty? || data.has_key?(:i18n))
             locales
           end
         end