[AIRFLOW-2766][Airflow-2766] Respect shared datetime across tabs
[AIRFLOW-2766][Airflow-2766] Respect shared datetime across tabs

Closes #3615 from verdan/AIRFLOW-2766-shared-
datetime

lxneng/incubator-airflow,lxneng/incubator-airflow,lxneng/incubator-airflow,lxneng/incubator-airflow