Payflow rejected for insufficient priviledges

Problem/Motivation

When 'Payflow' is used as the payment processor in Commerce, the process of pre-checking/authorizing and then creating and sending a transaction are missing the credentials and are being denied by PayFlow.

Steps to reproduce

Setup as noted in the Documentation for PayFlow. Try to make a purchase.

Proposed resolution

There are already ways to get the vendor, partner, user, password, they just aren't being engaged when the paypal transaction is made. If you bring them in ($this->getVendor, etc) and add them to the transaction as per: https://developer.paypal.com/api/nvp-soap/payflow/payflow-pro/payflow-pr...
the transactions go through.

Remaining tasks

I have a patch that is working for me at the moment, and am happy to provide it although it has notes for me commented out. (attached)

User interface changes

No changes needed.

API changes

Only need is the one I mention above.

Data model changes

No changes needed.