WooCommerce Product Documents 1.15.2

* Fix - When using a single or double quote in a Product Documents Title field, make sure the text is unescaped for display purposes
* Misc - Drop support for PHP v5.2: PHP v5.3 is now the minimum supported version
* Misc - Update SkyVerge plugin framework to version 5.3

* Misc - Add support for WooCommerce 3.5

* Fix - Replace use of jQuery `$.live()` function with `$.on()`