add unit tests for WebHdfsSensor

Airflow 1.10.1 released

Apache Airflow 1.10.1 RC1

Version 1.10.1b1

[AIRFLOW-XXX] Update changelog for 1.10

(cherry picked from commit 8b04e20)
Signed-off-by: Bolke de Bruin <bolke@xs4all.nl>

[AIRFLOW-XXX] Update changelog for 1.10

(cherry picked from commit 8b04e20)
Signed-off-by: Bolke de Bruin <bolke@xs4all.nl>

[AIRFLOW-XXX] Update changelog for 1.10

[AIRFLOW-1729][AIRFLOW-XXX] Remove extra debug log at info level

I left an extra log call, at info level in apache#3602
that was being used for
debugging.

Closes apache#3603 from ashb/remove-extra-log

(cherry picked from commit 7c19ed0)
Signed-off-by: Bolke de Bruin <bolke@xs4all.nl>

no incubating