Log Message:
Update ruby-httpclient to 2.2.4.

= Changes in 2.2.4 =
  Dec 08, 2011 - version 2.2.4
    * Bug fixes
      * Do not recycle buffer String object for yielding.  When the response is
        not chunked and the size of the response > 16KB, API with block style
        yields recycled String object for each yields.
      * Set VERSION string in User-Agent header.  $Id$ didn't work long time...
      Bugs are reported by Seamus Abshere. Thanks!