AuditActionExecutor: factored out case distinction into separate method.

[reinhardt]

Refs #18

The new process_action method can be overridden in custom adapters to handle other event types while still reusing the basic processing that remains in the __call__ method.

[ale-rt]

I reworked your idea in #20.
I think that #20 should be preferable because it slims down further the __call__ method and avoids inspecting the stack when it is not needed.
Let me know what you think about #20 and if it solves your issue.

[pilz]

I cannot fully judge it but it seems a fair approach to me. Given the fact that we are in holiday season and this fix is of high benefit for the customer (and us because it can potentially reduce our manual fixing effort a lot) I want to opt to merge #20 now so that we can improve the situation of case creation rather sooner than later.

[ale-rt]

Superseded by #20