Update plugin-name.php

return plugin instance in every case. Otherwise plugin will be disabled when EDD core gets updated
Update class.extension-activation.php

Remove deactivation process. Notification is enough here. Otherwise this plugin gets deactivated permantely and automatically when core EDD is updated.
Update plugin-name.php

register_activation_hook out side of the main class
Merge pull request #6 from RaceRay/master

Create register_activation_hook and prevent plugin be disabled when core gets updated