Keep track of the created mount directories

And remove them after umount

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
Be a little bit safer when removing a created mount directory

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
Support deeper mount points that the root directory for tracking

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>