Version 2 API only.

`setAffiliate`

Attaches a cart to an affiliate

Method Signature	boolean ultraCart.setAffiliate(String affiliateId, String subId, opts);
Description	Attaches a cart to an affiliate, and updates the cart
Parameter	affiliateId- the affiliate's id
Parameter	subId - the affiliate's sub id
Parameter	opts - see Making an Asynchronous Call
Result	true if successful, otherwise false