Feature Request: custom operation name in middleware

[AgDude]

The current implementation of the DjangoTracing class forces the use of view_func.__name__ as the operation name for the span. I have a use case with class based views where the view func ends up being the same, but they are distinct operations. I would like the ability to customize this without overriding the entire _apply_tracing method.

Perhaps accept a kwarg for operation name so subclasses could handle it.