Givewp: Fix currency code for "Iranian rial"

[ravinderk]

Issue Overview

The Currency code for "Iranian Rial" is in code RIAL instead of IRR.
https://github.com/WordImpress/Give/blob/9fc6c7c583a7713914fd823935cab149a5e08c40/includes/misc-functions.php#L97

For Ref:
https://github.com/woocommerce/woocommerce/blob/fcb7da5599f85df37e423e8195810f1e81bbae83/includes/wc-core-functions.php#L360

https://en.wikipedia.org/wiki/Iranian_rial

Todos

• [ ] Tests
• [ ] Documentation

[ravinderk]

We can not replace RIAL immediately with IRR because currency code attaches to many logic. In some case, we store it in the database also.

[raftaar1191]

Small issues need to fixed this as well
http://screencast-o-matic.com/watch/cbliln2Cr4

I Have also check with Euro it's working fine for it

[ravinderk]

Opened by mistake, I will reopen this when @raftaar1191 will reconfirm issue.