[action] add generic order action. (cherry picked from commit 6f8245d74ee9a333955a6d8a81027bde9e4f6673)

Conflicts:

	src/Payum/Paypal/ProCheckout/Nvp/PaymentFactory.php
[request] add getFirstModel method to Generic request.
[request] update doc of done script.
Merge branch '0.12'

Conflicts:
	src/Payum/Core/Resources/docs/done-script.md