Adyen Payment 1.4.0

Features:

#39 Added PayByMail functionality
#40 Added Sepa API for backend payments
#41 Added Maestro and UnionPay as creditcard methods

Fixes:

Correct name private variable and paypal one click,recurring fix
Added own backend template for payment method adyen POS
Fix undefined variable code in template file for adyen sepa
Fix exception when recurringContract is not found for cronjob
Added missing adyen_sepa template for mail