Disable logging in test

It makes it faster.
Use poltergeist instead of capybara-webkit

Poltergeist is a phantomjs driver for capybara. We've had trouble
installing newer versions of webkit on the CI servers wheras phantomjs
has an easy to use binary which we can reliably install.

Phantomjs also gives stack traces from javascript errors which is very
useful.
Update to version 0.6 of poltergeist.
Remove ruby-debug19 from Gemfile.
We don't use rvm on jenkins.
Go back to capybara-webkit instead of poltergeist.

There are a couple of intermittent errors on CI with poltergeist and I
don't have time to debug them.

This reverts commit 74d3a7d63a3d024d36858330e95c8aa7bd6967e2.

The errors are:

test: Employed person who started 26 weeks before qualifying week (which
is in the future), changing due date should prefill the date selections.
(MaternityAnswerJavascriptTest):
Capybara::ElementNotFound: Unable to find css
"select[name='response[day]']"
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/capybara-1.1.2/lib/capybara/node/finders.rb:154:in
`raise_find_error'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/capybara-1.1.2/lib/capybara/node/finders.rb:27:in
`block in find'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/capybara-1.1.2/lib/capybara/node/base.rb:46:in
`wait_until'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/capybara-1.1.2/lib/capybara/node/finders.rb:27:in
`find'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/capybara-1.1.2/lib/capybara/node/element.rb:177:in
`block in find'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/capybara-1.1.2/lib/capybara/node/base.rb:46:in
`wait_until'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/capybara-1.1.2/lib/capybara/node/element.rb:177:in
`find'
    (eval):2:in `find'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/capybara-1.1.2/lib/capybara/dsl.rb:161:in
`find'
    /mnt/jenkins/workspace/Smart_Answers/test/integration/maternity_answer_logic.rb:134:in
`block (6 levels) in should_implement_maternity_answer_logic'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/capybara-1.1.2/lib/capybara/session.rb:192:in
`within'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/capybara-1.1.2/lib/capybara/dsl.rb:161:in
`within'
    /mnt/jenkins/workspace/Smart_Answers/test/integration/maternity_answer_logic.rb:133:in
`block (5 levels) in should_implement_maternity_answer_logic'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/shoulda-2.11.3/lib/shoulda/context.rb:382:in
`call'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/shoulda-2.11.3/lib/shoulda/context.rb:382:in
`block in create_test_from_should_hash'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/mocha-0.10.0/lib/mocha/integration/mini_test/version_142_to_172.rb:27:in
`run'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/activesupport-3.1.3/lib/active_support/testing/setup_and_teardown.rb:35:in
`block in run'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/activesupport-3.1.3/lib/active_support/callbacks.rb:417:in
`_run_setup_callbacks'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/activesupport-3.1.3/lib/active_support/callbacks.rb:81:in
`run_callbacks'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/activesupport-3.1.3/lib/active_support/testing/setup_and_teardown.rb:34:in
`run'

  2) Error:
test: Employed person who started 26 weeks before qualifying week (which
is in the future), changing due date should redisplay the question.
(MaternityAnswerJavascriptTest):
RuntimeError: Expected question 'When is your baby due?', but found '4
Will you still be in the same job on 12 August 2012?'
    /mnt/jenkins/workspace/Smart_Answers/test/integration/smart_answer_test_helper.rb:9:in
`rescue in expect_question'
    /mnt/jenkins/workspace/Smart_Answers/test/integration/smart_answer_test_helper.rb:5:in
`expect_question'
    /mnt/jenkins/workspace/Smart_Answers/test/integration/maternity_answer_logic.rb:129:in
`block (5 levels) in should_implement_maternity_answer_logic'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/shoulda-2.11.3/lib/shoulda/context.rb:382:in
`call'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/shoulda-2.11.3/lib/shoulda/context.rb:382:in
`block in create_test_from_should_hash'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/mocha-0.10.0/lib/mocha/integration/mini_test/version_142_to_172.rb:27:in
`run'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/activesupport-3.1.3/lib/active_support/testing/setup_and_teardown.rb:35:in
`block in run'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/activesupport-3.1.3/lib/active_support/callbacks.rb:417:in
`_run_setup_callbacks'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/activesupport-3.1.3/lib/active_support/callbacks.rb:81:in
`run_callbacks'
    /home/jenkins/bundles/Smart_Answers/ruby/1.9.1/gems/activesupport-3.1.3/lib/active_support/testing/setup_and_teardown.rb:34:in
`run'