add payment gateway for wpgive

Hi there,

Here’s what I’d suggest if you want to build out your own gateway.

1) Review our code in the core Give plugin found in “wp-content/plugins/give/includes/gateways/”

2) Read through this article our colleague Chris Flannagan wrote on the subject: https://whoischris.com/building-payment-gateway-give-wp-donation-plugin-wordpress/

Thanks!