Log Message:
Update ruby-nokogiri to 1.5.5.

== 1.5.5 / unreleased

* Features

  * Much-improved support for JRuby in 1.9 mode! Yay!

* Bugfixes

  * Regression in JRuby Nokogiri add_previous_sibling (1.5.0 -> 1.5.1) #691
    (Thanks, John Shahid!)
  * JRuby unable to create HTML doc if URL arg provided #674 (Thanks, John
    Shahid!)
  * JRuby raises NullPointerException when given HTML document is nil or empty
    string. #699
  * JRuby 1.9 error, uncaught throw 'encoding_found', has been fixed. #673
  * Invalid encoding returned in JRuby with US-ASCII. #583
  * XmlSaxPushParser raises IndexOutOfBoundsException when over 512 characters
    are given. #567, #615
  * When xpath evaluation returns empty NodeSet, decorating NodeSet's base
    document raises exception. #514
  * JRuby raises exception when xpath with namespace is specified. pull
    request #681 (Thanks, Piotr Szmielew)
  * JRuby renders nodes without their namespace when subclassing Node. #695
  * JRuby raises NAMESPACE_ERR (org.w3c.dom.DOMException) while instantiating
    RDF::RDFXML::Writer. #683
  * JRuby is not able to use namespaces in xpath. #493