New: Added support for selecting specific price IDs.
Fix: Not working with the latest version of Software Licensing.
Fix: PHP notice when saving a download without activating Free Download.
Tweak: Updated to use EDD's build in license handler.
Tweak: Improve saving product settings to avoid undefined index errors, and to not save empty settings.
Tweak: Move settings to a separate "License Free Downloads" section.
Tweak: Move the Free Download meta box, reduce the priority, and use EDD core's built-in product dropdown.
