Log Message:
Update rabbit to 2.1.0.

== 2.1.0: 2013-06-16

A bug fix release of 2.0.9.

=== Improvements

==== rabbit

  * Ignored backup files when detecting a README file.
    [GitHub:#21] [Reported by TOMITA Masahiro]
  * Added Ruby version check on RubyGems install.
    If you install with Ruby 1.8, RubyGems reports an error.

=== Fixes

==== rabbit

  * Fixed a bug that encoding conversion error handling is bad.
    [Reported by Junichi Oya]
  * Supported Ruby/GLib2 2.0.2 or ealier.

=== Thanks

  * TOMITA Masahiro
  * Junichi Oya