Log Message:
Update ruby-i18n to 0.7.0.

0.7.0
* Drop support to Ruby 1.8.7 / REE
* Drop support to Rails 2.3 / 3.0 / 3.1
* Remove deprecated stuff:
   - Setting :default_exception_hander Symbol to I18n.exception_handler.
   - normalize_translation_keys in favor of normalize_keys.
   - :rescue_format option on the exception handler.
   - enforce_available_locales now defaults to true with no deprecation message.