fly

@dyu Don't actually want to make PR, because I don't want to install all the dependencies to make clean test before submitting it :blush: But code would be something like...

I see, thank you for explanation. I'm currently using workaround for this but I will try to submit PR once I have a little bit more free time.

Now when python 3.7 is released I can use its `contextvars` module and custom log record factory to achieve what I need easily. @asvetlov or others please decide if this...

Well, couple of lines that read/write contextvar seems to be much more maintainable and easy option than redefining `AccessLogger` and `Application`, which is not supposed to be subclassed at all....