3 minor issues

[racitup]

Firstly in modifiers.py, commision_percentage has a typo and should be commission_percentage
Secondly the modifier doesn't support the additional fixed charge (of 20p in the UK)
Thirdly (and the most difficult to fix) the modifier doesn't deal with the different charge for European vs non-European cards:

[jrief]

Even though this is an old issue, do you know where Stripe offers an endpoint to fetch these fees?