chore(backend): updated swagger documentation

[allynt]

Updated swagger documentation for UserViewSet

[marksmall]

I did a bit of investigation into these test failures and found a couple of tests failing

• test_user_serializers.py - AttributeError: 'tuple' object has no attribute 'items' in overridden to_representation method of UserSerializerBasic.
• test_user_views.py - AssertionError: The.update()method does not support writable nested fields by default in the overriden update mothod of UserSerializerBasic.

The former, in the to_representation overridden method, the self parameter when printed in the debugger states the AttributeError: 'tuple' object has no attribute 'items', and the error is thrown when we call the super().to_representation(instance)

The latter view test is when we test updating a user, since we have a new serializer, it cannot update it's nested fields. I'm not sure what we want here, should the customer in this case be read_only, or do we add an update method, to the UserSerializer class.

[allynt]

@marksmall - the errors occurred b/c I didn't include the class Meta section for my serializer. Oops. In the end, I refactored a bit more and wound up using a standard serializer (rather than a ModelSerializer) - since as of the refactoring that serializer is only used for swagger documentation purposes.

[marksmall]

@allynt I guess your branch might be out-of-date as there are Conflicting files. If you fix those, I'm more than happy to review.