Update nokogiri

gollum-lib.gemspec

@@ -26,7 +26,7 @@ Gem::Specification.new do |s|
   s.add_dependency('github-markdown', '~> 0.5.3')
   s.add_dependency('pygments.rb', '~> 0.4.2')
   s.add_dependency('sanitize', '~> 2.0.3')
-  s.add_dependency('nokogiri', '~> 1.5.6')
+  s.add_dependency('nokogiri', '~> 1.5.9')
   s.add_dependency('stringex', '~> 1.5.1')
   s.add_development_dependency('RedCloth', '~> 4.2.9')