Add priority to operations imported to frepple

[steveblamey]

uzERP operations have an operation number that must be used as the priority for routing operations imported into frepple. This ensures that the operations are planned in the correct order.

This requires adding a priority column to the operations postgres view and also adding that to the erp2frepple.py management command python script.

[steveblamey]

Need to sync the schema files with the dev-cli https://github.com/uzerpllp/uzerp-dev-cli