Remove SpreeSkrill engine

Cant see any use for it and it was causing routes errors because it
loaded routes.rb file twice and therefore defined the same named route
twice
Clean up rspec DEPRECATION WARNINGs
Include FactoryGirl::Syntax::Methods in spec_helper
Specify branch for spree/spree dependency so that we can use local overrides
prepend routes so that they are only drawn once
Fix issue where skrill_status_update was being defined twice
support charging card token and customer card id

https://github.com/Shopify/active_merchant/issues/770

Fixes #93
Use Braintree's card type detection instead of shoehorning into ActiveMerchant's

Fixes #100

Conflicts:
	app/models/spree/gateway/braintree_gateway.rb
PAYMILL Integration

Fixes #101
Remove attr_accessible call from Paymill gateway
Added fatzebra support via ActiveMerchant

Fixes #98
Ensure different credit card types are converted before being passed to Braintree