fix purchase transaction_type to sale
check signed data on request response
fix getTransactionReference function to refer to correct field
fix enotice on cardTypes
linefeed [PSR-2] All PHP files must use the Unix LF (linefeed) line ending.
fix syntax duplication
change abstract request to not implement request interface, inconsistent with other gateways.
I think I did this when working on the tests - but removing doesn't break them
Merge pull request #4 from eileenmcnaughton/master

A couple of fix-ups on the purchase flow