Log Message:
Update ruby-gettext to 3.0.0.

## <a id="3-0-0">3.0.0</a>: 2013-08-31

This is a new major version up release!

This release removes many deprecated APIs and improves internal
APIs. We want to keep backward compatibility as much as possible but
some existing codes may be broken by gettext gem API change. If your
code breaks by gettext gem 3.0.0, please report your problem. We will
fix the problem and release a new version.

### Improvements

  * Removed deprecated APIs
    * `require "gettext/parser/erb"`.
       Use `require "gettext/tools/parser/erb"` instead.
    * `require "gettext/parser/glade"`.
      Use `require "gettext/tools/parser/glade"` instead.
    * `require "gettext/parser/ruby"`.
      Use `require "gettext/tools/parser/ruby"` instead.
    * `require "gettext/utils"`.
      Use `require "gettext/tools"` instead.
    * `GetText.msgmerge`. Use `GetText::Tools::MsgMerge.run` instead.
    * `GetText.create_mofiles`. Use `GetText::Tools::Task` instead.
    * `GetText::PoParser`. Use `GetText::POParser` instead.
    * `require "gettext/tools/poparser"`.
       Use `require "gettext/po_parser"` instead.
    * `require "gettext/runtime/mofile"`.
       Use `require "gettext/mo"` instead.
    * `GetText::MoFile`. Use `GetText::MO` instead.
    * `GetText::Task`. Use `GetText::Tools::Task` instead.
    * `GetText.set_locale_all`. Use `GetText.set_locale` instead.
    * `GetText.setlocale`. Use `GetText.set_locale` instead.
    * `GetText::Tools::MsgMerge::PoData`. Use `GetText::POEntry` instead.
  * Removed Ruby 1.8 support.
  * Supported Rake 10.1.0.
  * Stopped to remove `TRANSLATORS:` tag because GNU gettext doesn't
    remove it.
  * Stopped to use `TRANSLATORS:` as comment tag. It is GNU gettext
    compatible behavior.
  * rxgettext: Added `--add-comments[=TAG]` option that exists in
    xgettext. [GitHub #16] [Reported by Ladislav Slezák]
  * Supported escaping tab character as `\t`.

### Fixes

  * po: Added a missing new line for multiple extracted comments.
    [GitHub #17] [Patch by Ladislav Slezák]
  * Fixed a bug that encoding may not be set.
  * Fixed a bug that `\n` is escaped as `\\n`.
    [GitHub #18] [Debian #716916] [Reported by Ladislav Slezák]
    [Reported by Francesco Poli]

### Thanks

  * Ladislav Slezák
  * Francesco Poli

## <a id="2-3-9">2.3.9</a>: 2013-04-21

This is a msgmerge updated release.

### Improvements

  * [tools] Used the more modern word "cannot" instead of "can
    not". [GitHub #15] [Patch by Benjamin Kerensa]
  * Cleared license descriptions. [Suggested by Jérémy Bobbio]

### Fixes

  * Avoided including native extentions in this gem for Windows users.

### Thanks

  * Benjamin Kerensa
  * Jérémy Bobbio