API: ajout samples + amélioration des tests

app/api/billets_absences.py

app/api/departements.py

app/api/etudiants.py

app/api/evaluations.py

app/api/formations.py

app/api/formsemestres.py

app/api/jury.py

app/api/justificatifs.py

app/api/logos.py

app/api/moduleimpl.py

app/api/partitions.py

app/api/users.py

app/models/groups.py

tests/api/dump_all_results.py

tests/api/essai_tous_semestres.py

tests/api/exemple-api-basic.py

tests/api/exemple-api-list-modules.py

tests/api/make_samples.py

tests/api/setup_test_api.py

tests/api/test_api_assiduites.py