G-analytics-writer

2020.10.19
packaging fix

2020.10.13
* breaking change:
changed kwarg `async` to `render_async`, because `async` is a python3 keyword
* upgraded black
* integrated with pre-commit
* tox and github testing

2019.09.19
* black formatting

2019.04.26
* undid some aggressive 2to3 translations

2019.04.25
* official Python3 support. it worked before, but was not officially supported.
* renamed `custom_json_dumps` to `json_dumps`
* added `json_dumps_callable` to `AnalyticsWriter.__init__`
* removed monkeypatching of json dumper in test, specify into writer
* migrating charset to the front of the payload, per RFC

2018.10.08
* initial (limited) support for AMP format
* added some classes as attibutes of `AnalyticsWriter`