Feature request: configurable file name

[Bercof]

As a user I want to get returned file based on my request. For example, I whant to return file name based on request path:

• GET /users -> will return file name 'users_list.xlsx'
• GET /users/2 -> will return file name 'user_2_details.xlsx'

That is pretty easy to do: add to XLSXFileMixin.get_filename method parameters (self, request, *args, **kwargs) and pass them from finalize_response method. Thus developer may override XLSXFileMixin with correct file name getter based on request processing.

[willtho89]

@Bercof i have implemented your suggestion. Its in the release 0.4.3