Deploy app using Heroku to the MTurk Sandbox.

def sandbox(verbose, app):
    """Deploy app using Heroku to the MTurk Sandbox."""
    # Load psiTurk configuration.
    config = PsiturkConfig()
    config.load_config()

    # Set the mode.
    config.set("Experiment Configuration", "mode", "sandbox")
    config.set("Server Parameters", "logfile", "-")

    # Ensure that psiTurk is in sandbox mode.
    config.set("Shell Parameters", "launch_in_sandbox_mode", "true")

    # Do shared setup.
    deploy_sandbox_shared_setup(verbose=verbose, app=app)