Update ruby-actionpack to 2.1.1.

Changes:

* All 2xx requests are considered successful [Josh Peek]

* Deprecate the limited follow_redirect in functional tests.  If you
  wish to follow redirects, use integration tests. [Michael Koziarski]

* Fixed that AssetTagHelper#compute_public_path shouldn't cache the
  asset_host along with the source or per-request proc's won't run
  [DHH]

* Deprecate define_javascript_functions, javascript_include_tag and
  friends are much better [Michael Koziarski]

* Fix polymorphic_url with singleton resources.  #461 [Tammer Saleh]

* Deprecate ActionView::Base.erb_variable. Use the concat helper
  method instead of appending to it directly.  [Jeremy Kemper]

* Fixed Request#remote_ip to only raise hell if the HTTP_CLIENT_IP and
  HTTP_X_FORWARDED_FOR doesn't match (not just if they're both
  present) [Mark Imbriaco, Bradford Folkens]

(minskim)