[patch] IntegrationTest not propagating method_missing when appropriate

AC::IntegrationTest:

• derives from AS::TestCase.
• has a method_missing which delegates methods to its Session object.
• does not propagate the method_missing to its superclass if the Session object does not respond_to? the method.

This kills RSpec's IntegrationExampleGroup, as RSpec implements matchers like be_* via method_missing by mixing its Matchers module into AS::TestCase. I consider this to be a bug in IntegrationTest--it should propagate method_missing to its superclass if the session object can't handle it. Patch attached.

To reproduce the issue:

gem install rails rspec-rails
rails testapp
cd testapp
script/generate rspec
mkdir spec/integration
$EDITOR spec/integration/integration_spec.rb

Add the following:

require 'spec/spec_helper'

describe "Integration example groups", :type => :integration do
  it "should have RSpec matchers available" do
    true.should be_true
  end
end

Then:

rake db:migrate
rake spec:integration