v3 BILL network changes

In v3, there are a range of improvements and new features with BILL network operations.

v2	v3
Search the BILL network for a customer or vendor with `POST /v2/NetworkSearch.json`. Search the BILL network for a verified national vendor with `POST v2/LargeBillerSearch.json`.	With `GET /v3/network`, you can search for vendors, customers, and verified national vendors. This is a GET operation. The request and response field names have changed. All request fields are now query parameters and the organization `name` is required. You can set `networks` to search the BILL network, verified national vendor network, or both (`?networks=BILL,RPPS`). In the response, the vendor PNI for each vendor is available in the search results. In addition, the verified national vendor PNI (`id`) and billing address `id` for each verified national vendor is available. See BILL network in the API reference for more information.
Invite a customer or vendor in the BILL network with `POST /v2/SendInvite.json`. Connect verified national vendor as your vendor with `POST /v2/ConnectLargeBillerAsVendor.json`. `addressId` is required to uniquely identify a verified national vendor billing address. Get this address ID with `POST /v2/GetLargeBillerPaymentAddress.json`.	Sending a vendor invitation with `POST /v3/network/invitation/vendor/{vendorId}` combines 2 operations. `vendorId` is now set as a path parameter. 1. Send an invitation to a vendor. When the vendor accepts the invitation, your organization is connected with the vendor. 2. Connect with a verified national vendor. The request and response field names have changed. Accept a network invitation with `POST /v1/network/invitation/accept`. See Send vendor invitation and Accept network invitation in the API reference for more information.
Get invitation status with `POST /v2/GetNetworkStatus.json`.	Get vendor invitation status with `GET /v3/network/invitation/vendor/{vendorId}`. `vendorId` is now set as a path parameter. The response field names have changed. See Get vendor invitation status in the API reference for more information.
Cancel an existing invitation with `POST /v2/CancelInvite.json`. An invitation request `id` is required to identify the invitation. Get this `id` from the `POST /v2/CancelInvite.json` or `POST /v2/GetNetworkStatus.json` response.	Delete vendor invitation with `DELETE /v3/network/invitation/vendor/{vendorId}`. This is a DELETE operation. `vendorId` is now set as a path parameter. See Delete vendor invitation in the API reference for more information.