promotion 5.x-1.8

I'm finally applying the patches that have been waiting for a couple weeks and added in a feature that's been missing from the beginning but should have been there all along:

• Issue #154238: Promotions can now be deleted.
• Issue #152969: The settings form for promotions allowed you to tell the module whether a promotional code is required or not. However, it didn't give any feedback on whether the setting was actually taking effect. It was working, but it was impossible to tell from the form. This is now fixed.
• Issue #154240: This is a minor improvement to the internals where a form should have returned a URL rather than using drupal_goto(). There's no functional difference.