tests: dataapi tests refactorisation and fixes
tests: dataapi tests refactorisation and fixes

Previous version of assertion that was counting queries was not work
as expected. Also more test has been added and futher simplifications
has been applied.

jrutila/django-settings,jperelli/django-settings,jperelli/django-settings,jrutila/django-settings,jrutila/django-settings,jrutila/django-settings,jperelli/django-settings,jperelli/django-settings