Offline transactions and option to authorise only

* Added support for recording PinPayments transactions offline.
* Added option to capture and authorise imediatelly, or only postpone capture until invoice creation.
@jonpday Can you please review?
@andrew-dwyer given that these elements are inputs, does that mean that the CC number and other sensitive data will be submitted as part of the form POST when the order is placed? should the JS clear or disable those elements after the AJAX response from PIN is received back?