Add Item and ItemBag classes
Add PayPal Express line items
Add AbstractRequest::formatCurrency() method
Add item description parameter
Update PayPal item details
Merge branch 'line-items'
Add RequestInterface::sendData() method
Update gateways to use new sendData method
Merge pull request #162 from adrianmacneil/custom-send-data

Custom send data parameters
Merge branch 'master' of https://github.com/adrianmacneil/omnipay