Apache Airflow 2.0.0beta2 available for testing

[Ash Berlin-Taylor <as...@apache.org>]

Following closely on the heels of beta1, it's beta2 time!

The beta snapshot is available at:
https://dist.apache.org/repos/dist/dev/airflow/2.0.0b2 (https://dist.apache.org/repos/dist/dev/airflow/2.0.0b2/)/ (https://dist.apache.org/repos/dist/dev/airflow/2.0.0a1/)
*apache-airflow-2.0.0b2-source.tar.gz* is a source release that comes with INSTALL instructions.
*apache-airflow-2.0.0b2-bin.tar.gz* is the binary Python "sdist" snapshot.
*apache_airflow-2.0.0b2-py3-none-any.whl* is the binary Python wheel snapshot.
This snapshot has been pushed to PyPi.
Major features since beta1:
* Added missing api_connextion/__init__.py so that the new REST API works again (#12240)
* Fixes automated provider installation with extras so that pip install --pre apache-airflow[amazon] works as intended. (#12233)

Please note that some of the "extras" are broken, for instance apache-airflow[stats] won't correctly install statsd. For now work around this by running `pip install apache-airflow statsd` instead. We will fix these in beta3, which will be next week (unless something more crticial comes up in the mean time)
We have also pushed out the 1.0.0b1 of the sendgrid provider that was (knowingly) missed in the first batch.
-ash