Log Message:
Update rubygems to 1.8.25.

=== 1.8.25/ 2013-01-24

* 6 bug fixes:

  * Added 11627 to setup bin_file location to protect against errors.
    Fixes #328 by ConradIrwin
  * Specification#ruby_code didn't handle Requirement with multiple
  * Fix error on creating a Version object with a frozen string.
  * Fix incremental index updates
  * Fix missing load_yaml in YAML-related requirement.rb code.
  * Manually backport encoding-aware YAML gemspec