Monkey Patch Octopress

Based on post_filters by imathis.

First Move the original method out the way with alias_method then create a new method with the original name, calling the original now aliased method if required.

module Jekyll
  class URL
    alias_method :old_sanitize_url, :sanitize_url
    def sanitize_url(in_url)
      old_sanitize_url(in_url).downcase
    end
  end
end

This was used to build my Octopress plugin octopress_url_downcase.