WooCommerce Social Login 2.16.0

* Misc - Add support for WooCommerce 3.6
* Misc - Require PHP 5.4+

* Fix - As PayPal may not allow sharing users email addresses without approval, do not require email for new installations and let users that sign in with PayPal provide one manually instead
* Dev - Add filter hook to alter the request scope of PayPal profile fields and add more fields
* Dev - Remove SkyVerge Framework methods from template files for better backwards compatibility

* Dev - Add filter to toggle loading of frontend scripts in the footer instead of head of the document page
* Misc - Add support for WooCommerce 3.5