Donation system mostly there, Some Payee model fields have been moved out into Service model

 - 'donation.checkout' API method can now create WePay checkouts based on the recipient_id + entity_id given.
 - Payee model doesn't hold service user details they have been moved into a Service model so multiple payees can share a single service user.
 - WePayPaymentPlatform handler now creates Service and Donation model items.
 - /account/payee/add lists linked accounts (Payee User Services) now
 - Payee now stores 'account_name' to allow user easier payee validation.