Remove double spacing
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
Fix failing data cash remote unsuccessful capture test
Add functionality to enable card pre registration with data cash

Conflicts:
	lib/active_merchant/billing/gateways/data_cash.rb
Switch data cash tests from deprecated DataCashGateway#credit to #refund

If #credit is being used with a credit card rather than a ca_reference
as an argument then we cannot migrate - These tests will break when the
\#credit method is removed