Merge 'Develop' into master

Merge 'develop' branche

loosen version requirements to permit install on magento 2.0.x

loosen version requirements to permit install on magento 2.0.x

#72 add refunded amount to adyen_order_payment table, fix multiple refunds on same pspreference for split payments, show split payments in overview payment information of the order and add column original_reference to notification table.

 #61 send in extra data for openinvoice and fix result hmac calculation so it alllow to have dots in the result params

#67 fix country validation for all payment methods and do not include config model into Sepa validation because it is not needed

#67 fix skinCode for PayByMail and added genericConfigProvider for general setting to show icons or not

#67 remove adyen_generic_config_provider because does not exsists anymore and remove Method folder because now using facade impl.

#67 Adyen PayByMail is now using the Facade implementation and fixes that HPP and POS are not available for backend orders, removed unused variable in OneClick form block removed unused AdyenAbstract method.