Breaking changes

drop support for SHA1, replace with support for SHA256
As of July 2016 Adyen no longer supports version one HPP skins which used SHA1, please update your skins to work with SHA256 in the Adyen Customer Portal.
Spree::Adyen::Form is renamed to Spree::Adyen::HPP
if you injected custom params into the form it should continue to work so long as you fix the constant name, but wholesale replacement of form params will not as additional fields are required for SHA256

Fixes