Fix 'REFUNDSTATUS' string; Refactor to doCapture method

Fix 'REFUNDSTATUS' string; Refactor to doCapture method
Update ExpressCheckoutPlugin.php
Fix array collection

Get first deposit transaction from current payment.
Use transactionid from response

Normally the transaction id is the same as the authorized id, but to be more clean.
dependency to modified core bundle
Merge branch 'flexible_payment_instruction' of https://github.com/sveriger/JMSPaymentPaypalBundle into flexible_payment_instruction