Add SDO OCS Voucher Validation API ?

[t-fine]

This would be used by the UI team to validate vouchers during import, so they don't have to do the same parse, they can just call the API. Not sure if we can validate enough to make this worthwhile, or if it is better for the UI just to respond to import errors. Also, not sure how well this would work on a tar file of 100's of vouchers.