Add Project: Airflow

[xmatthias]

Basic info

Application name: Airflow Application repo link: https://github.com/apache/airflow/ Application home link: https://airflow.apache.org/ Application description: Airflow is a platform to programmatically author, schedule and monitor workflows.

Qualifications

There are a ton of great Python projects out there, but what makes an application "Awesome™"? Please check that all of the following criteria apply:

• [X] Free software with an online source repository.
• [X] Using Python for a considerable part of their functionality.
• [X] Well-known, or at least prominently used in an identifiable niche.
• [X] Maintained or otherwise demonstrably still functional on relevant platforms.
• [X] An application, not a library or framework.
• [x] Installable via PyPI (https://pypi.org/project/apache-airflow/)

Additional notability info

closes #116

[mahmoud]

Good one, thank you!