Pins flask-admin to 1.4.0

[hotfix] flask admin 1.4.1 break production, pinning 1.4.0

Bump version to unblock pypi release

[AIRFLOW-52] 1.7.1 version bump and changelog

Fix : Don't treat premature tasks as could_not_run tasks

Merge pull request apache#1422 from stranbird/conn-ui-revamp

Show `extra` data on the connection list view

Revert "Tasks references upstream and downstream tasks using strings …

…instead of references"

This reverts commit 6c1207b.

Revert "Tasks references upstream and downstream tasks using strings …

…instead of references"

This reverts commit 6c1207b.

Missing comma in setup.py