fix: avoid confirmed rfq at installation

This module adds a type selection field (rfq, bid, or purchase). It
correctly takes care to change the type as the workflow progresses, but
existing data (including demo data created by core modules) is left in
inconsistent states. Specifically, there are o few RFQs in state
Confirmed.

This fixes the situation when the module is installed. Migration scripts
cannot be used at installation anymore, so I use the new v8 hooks.
add docstring to post init hook
use SUPERUSER_ID and PO
Merge pull request #55 from lepistone/fix-inconsistent-purchase-type

fix: avoid confirmed rfq at installation