Never start if status is not NULL.
Never start if status is not NULL.

Don't throw an exception, just make the function return. That way the user will simply see the current status after attempting to start the newsletter.

Fixes #37.
jonmifsud/email_newsletter_manager,creativedutchmen/email_newsletter_manager,creativedutchmen/email_newsletter_manager,jonmifsud/email_newsletter_manager