Fix typos in data cash comments
Update valid mastercard number for the data cash test gateway
Update data cash test response stubs to reflect the current api
Fix failing data cash tests using an invalid ca_reference arg
Update doc to explain the data cash authorization parameter
Added support to datacash gateway for refunds on transactions which were taken via continuous authority
Fix bug in DataCashGateway where authorize with continuous authority was actually a purchase
Move unreferenced data cash test AMOUNT constant to a referenced @amount ivar
Fixed so that currency option is respected when making a refund
Add functionality to enable card pre registration with data cash

Conflicts:
	lib/active_merchant/billing/gateways/data_cash.rb