Add CustomField searching to test_script.rb
Helix::Config.get_response now uses #massage_custom_fields_in to properly encode nested CFs; Specs
Add spec/_integration_spec.rb, intended to replace test_script.rb

The leading _ is to ensure that it runs first due to stubbing concerns - that should probably be fixed.
Flesh out more coverage in spec/_integration_spec.rb
Remove test_script.rb