Update Vendored Rack to 1.2.0

Also update tests for itextomml 1.3.25.

vendor/plugins/rack/spec/spec_nulllogger.rb

@@ -0,0 +1,12 @@
+require 'rack/nulllogger'
+
+describe Rack::NullLogger do
+  should "act as a noop logger" do
+    app = lambda { |env|
+      env['rack.logger'].warn "b00m"
+      [200, {'Content-Type' => 'text/plain'}, ["Hello, World!"]]
+    }
+    logger = Rack::NullLogger.new(app)
+    lambda{ logger.call({}) }.should.not.raise
+  end
+end