Update to use start_button_href helper
Update to use start_button_href helper

This commit updates the start button link href with the start_button_href

aledelcueto/smart-answers,alphagov/smart-answers,alphagov/smart-answers,aledelcueto/smart-answers,aledelcueto/smart-answers,alphagov/smart-answers,aledelcueto/smart-answers,alphagov/smart-answers