Database keeps changes through one class

Changes scope of fixture 'db' dynamically, depending on kwargs for pytest.mark.django_db.
Allows one class to keep all changes in databse and allows for incremental testing of database.

!!!! BUG !!!!
@pytest.mark.django_db(class_db=True)
class TestDB:
    # Tests now with classDB, but without transaction

    @pytest.mark.django_db(transaction=True)
    def test_smthg(self):
        # Tests with classDB and (newly activated) transactions:
   ##### mayjor breackdown!!!!!

@pytest.mark.django_db(True, True)
class TestBlah:
 ### no problem

Since I don't use transactions, I don't think I will fix this anytime soon. Furthermore it's a rather rare usecase I believe.