Initialise the prototype app for capybara.
Load env variables during testing to set the static assets govuk host.

Related to d791285f thanks @andrewgarner
Update booking journey content for showcase.

See: https://docs.google.com/a/digital.cabinet-office.gov.uk/document/d/1Pvhd4577BTcKdduZLlZZm2IiXgU5N0Oby_JxkKpeeFw/edit