Gravity Perks - Limit Checkboxes 1.3.18

Added gplc-disabled CSS class to checkboxes disabled by GP Limit Checkboxes to allow external scripts to safely identify (or ignore) checkboxes disabled by GP Limit Checkboxes.

Improved compatibility with GP Inventory when using Scoped Inventory.

Fixed issue with lower limits not being respected with spanned limits.
Improved compatibility with Gravity Forms 2.6 AJAX form saving.
Added "Update URI" to plugin header to improve security.