Update README.md
Remove constructor from GatewayInterface
Remove remote unit tests
Add PHP 5.5 to Travis
Add basic factory
Fix typo
Fix stripe request format
Add Payflow Pro gateway
Refactor to allow pluggable HTTP client libraries
Move gateways to billing namespace
Clean up httpRequest calls
Add Netaxept gateway
Add CardSave gateway
Add WorldPay gateway
Add numeric currency code support
Update CardSave gateway tests
Don't report PHP 5.5 errors