Merge pull request #1 from easydigitaldownloads/master

Merge to master
Fix issue on Gravity Forms' Edit Form page

> Notice: Undefined offset: 0 in `[...]/wp-content/plugins/easy-digital-downloads/includes/class-edd-roles.php on line 207`
Merge pull request #2559 from zackkatz/master

Fix undefined offset error in Gravity Forms