Pin pip version used by pipenv

Add Apache Airflow 1.10 Support

Update travis setup for Hatchet

Fix Python 3.6 message when using Python 3.7

Fix indentation levels

more helpful messages about supported versions

Hatchet/yay

Start adding dates to changelog entries

It's occasionally useful to see at a glance when releases were pushed to understand what release might have caused a customer's issues. This back-fills dates for the last few months of releases and sets a precedent that can be followed in the future.

update buildpack tests to expect success for all 2.7.15 builds

Add a Pull Request template

To try and help prevent the notification noise from PRs being opened
against upstream by mistake.

v 138 changelog