Refs #99 -- Improve support for currencies with less than 2 decimal places (#783)

* Refs #99 -- Fix stripe support for zero-decimal currencies

* Add new money formatting method

* Force decimal places in many places

* Locale-aware currency rendering

* Fix currencies in more places

* More currency fixes

src/pretix/plugins/paypal/payment.py

@@ -55,6 +55,8 @@ class Paypal(BasePaymentProvider):
                 ('client_id',
                  forms.CharField(
                      label=_('Client ID'),
+                     max_length=80,
+                     min_length=80,
                      help_text=_('<a target="_blank" rel="noopener" href="{docs_url}">{text}</a>').format(
                          text=_('Click here for a tutorial on how to obtain the required keys'),
                          docs_url='https://docs.pretix.eu/en/latest/user/payments/paypal.html'
@@ -63,6 +65,8 @@ class Paypal(BasePaymentProvider):
                 ('secret',
                  forms.CharField(
                      label=_('Secret'),
+                     max_length=80,
+                     min_length=80,
                  ))
             ]
         )