Automatically create non-existent bind-mounted directories on the host

Fixes #1279.

Docker-DCO-1.1-Signed-off-by: Maxime Petazzoni <max@signalfuse.com> (github: mpetazzoni)
Documentation about automatic bind-mount dir creation

Docker-DCO-1.1-Signed-off-by: Maxime Petazzoni <max@signalfuse.com> (github: mpetazzoni)
Merge pull request #2655 from mpetazzoni/create-local-bind-dirs

Automatically create non-existent bind-mounted host directories