Update forms.py

The default currency is USD but one can change it.
Merge pull request #36 from rafael-queo/patch-1

Added field currencycode to paypal.pro.forms.PaymentForm
README fix
Better admin for IPN objects
Merge branch 'master' of github.com:spookylukey/django-paypal

Conflicts:
	README.md
Added a BSD license
Fixed formatting in README
Sorted out license confusion