Task LSMR-14: Full specification model test coverage (DB and API) including tests for missing relations

Task LSMR-14: Functional test coverage of all models. Still missing some checks for missing relations.

Task LSMR-14: Added missing properties and altered relation attributes to match the current spec by the architect

Task LSMR-14: Reverted previously disimproved paths so that we have a working and contained package again; fixed model tests for new choices

LSMR-14: implemented (semi)static choices with foreignkeys and automatic population of the inital database.

models/serializers/viewsets

Task LSMR-13: fixed work io roles and added test coverage, renamed request relation template according to input by JDM