receiverInfo and walletProvider missing from payout instructions

[pieterpoorthuis]

If the wallet provider is listed in https://bitpay.com/api#reference-Wallet Providers ​a​n​d ​instruction a​m​o​u​n​t ​>​= ​$​3​0​0​0 U​S​D, the following two must be set:

1. walletProvider, the bitcoin wallet provider used by the customer to receive the funds
2. receiverInfo. Containing name, emailAddress, address (containing streetAddress1, streetAddress2, locality, region, postalCode and country)

Need getters and setters for the walletProvider and receiverInfo