Chargebee + Heartland Integration

Keep Chargebee and Heartland aligned: when finance events happen in one, update the other automatically.

Example: when Chargebee's "Watch Events" fires, WEXTL can "Add Item to a Purchase Order" in Heartland. Chargebee has 2 triggers (including Watch Events and Watch Events (Polling)); Heartland has 50 actions (including Add Item to a Purchase Order, Add Item to a Receipt, and Add Item to a Return).