Money Buster doesn't follow local language settings

Hello! I think this is a very nice project. I'm trying Cospend with Nextcloud and I think it has a lot of potencial.

However, I've found that when adding the money spent, the text field doesn't follow my Spanish language settings: we use commas as decimal separator instead of periods, but when I try to fill something like "15,45" I find that you can only writer numbers and one period.

Maybe this could be improved to follow the default language setting?

Again, thanks for the app!