Log entries should use appenlight.tags #31

Currently appenlight has two completely separate ways to define tags:

• the extrakeyword parameter for logging
• appenlight.tags in the environ for everything else

This means that to get the same tags in logging you have to use extra=<something> to every single log statement in your code. That quickly becomes very painful to do and maintain.

I would like to see logging use appenlight.tags as well, allowing you to use the extra parameter to add or override tags.