comment_notify 5.x-2.1

Changes since DRUPAL-5--2-0:

• feature #296549 by greggles idea by bchoc: if anonymous can't leave an email, hide the checkbox / provide help to admins to get the settings right
• task #290781 by greggles: comment cleanup, variable naming, removing unused code
• task #289726 by greggles: don't mail to blocked users:
• bug #297791 by greggles: deleted comments are not deleted from comment_notify
• bug #305259 by greggles: if a user can't subscribe to comments don't add form elements to their user edit screen
• bug #304926 by greggles: E-mails are sent only to registered users regression from 289726
• default to on for all node types
• coder style cleanups