range of vf:under, removed fulfillment ref

Since we got rid of ExchangeAgreement, I'm seeing a need to differentiate the agreements which are part of VF, and will be created along with commitments, etc. and agreements which are just referenced and will not be defined or created as part of VF. This removes agreements referenced by vf:under from VF.

Also took vf:under off of Fulfillment, probably not needed there, leaving on all the flows.