[*] MO : homefeatured choose cat and order by rand

* Added configuration field to choose Category ID to be used for getProducts
* Pick products from the given category *by random*
* defaults to Home category
[*] MO : homefeatured choose cat and order by rand

* Improved the code
* Made randomic ordering selectable too
// follow up https://github.com/PrestaShop/homefeatured/pull/1
Merge branch 'ZiZuu-store-patch-1' into dev