Begin refactoring requests into separate classes
Refactor Common and Dummy gateway request classes
Merge branch 'refs/heads/master' into refactor-requests
Add AbstractMessage and MessageInterface
Add Authorize.Net Request classes
Add CardSave request classes
Add GoCardless Request classes
Fix Dummy gateway error when CreditCard is missing. Closes #20
Add Netaxept Request classes
Rename example app completePurchase page
Add Payflow Request classes
Add Pin & Stripe Request classes
Add PaymentExpress Request classes
Add Sage Pay Request classes
Add WorldPay Request classes
Add 2Checkout Request classes
Support PHP 5.3.3
PHP 5.3.3 compatibility fixes
Add PHP version requirement
Remove old RedirectResponse classes