Simplified payment button customisation. #196

[fabiocaccamo]

With this PR it is possible to customise the payment button by doing just this:

from paypal.standard.forms import PayPalPaymentsForm

class CustomPayPalPaymentsForm(PayPalPaymentsForm):

    def get_html_submit_element(self):
        return """<button type="submit">Continue on PayPal website</button>"""

[spookylukey]

This looks like a nice improvement, thanks!

Would you be able to write some docs? I think a new section on overriding the form at the bottom of this page would be good: https://django-paypal.readthedocs.io/en/latest/standard/ipn.html

[fabiocaccamo]

@spookylukey I updated the docs adding the button customisation block and fixing a broken link.

[spookylukey]

Thanks!