Support multiple currencies

[mishawakerman]

I spend a lot of time doing back of the envelope EC2 pricing and this tool looks great!

I often forget to convert the currency or accidentally convert multiple times (when mixing and matching options). It would be great if there was a dropdown for selecting the currency.

There are free exchange rate APIs (like https://exchangeratesapi.io/) and this could be done from the frontend.

Happy to take a look at adding this if it's wanted.

[v9n]

That would be awesome. @mishawakerman