TestCase.assertEquals (note the s at the end) has been deprecated.
The only failing tests remaining are CSV related, which is not
surprising.

Fix to allow users to specify which cards they accept.
By default, this works exactly as it did- i.e., any number
can be entered and only a luhn check is run on it.
Users can now overide this behaviour by passing a list of
accepted cards as a 'types'kwarg to BankcardNumberField,
e.g.
BankcardNumberField(types=[bankcards.VISA, bankcards.VISA_ELECTRON,])

If this is specified, we check that the type of card is one we're
aware of and then that the card number matches the pattern for that
type of card

Fixes #949

@maikhoepfel rewrote the ImproperlyConfigured check using Python's sets.

Conflicts:
	oscar/apps/payment/forms.py

Fields now more self-contained, the bankcard form is much simpler.