Update ruby-gettext to version 1.90.0.  Changes from 1.10.0 include:

+ Install as a Ruby gem.

* Support Ukrainian(ua), Hungarian(hu)
* JRuby supported.
* Become a pure ruby library (Remove .so extention).
* Locale modules separate from lib/gettext/ to lib/locale/.
* Locale modules are refactored. System locales become read only.
* Fix bugs.
* Enhance to support Ruby on Rails.
  * error_messages_for can accept custom error dialog messages.
  * Add GetText::Rails.available_locales, .normalized_locale
    and fragment_cache_key/expire_fragment reimplement to use these methods
    to restrict cached locale files.

(jlam)