check: "autofs" feature added

The only way to check, whether autofs migration is supported  from the kernel
side is to check actual mount point options (search for "pipe_ino" option).
This checker first tries to find autofs on host. If there is no any, temporary
mounts autofs by itself.

Signed-off-by: Stanislav Kinsburskiy <skinsbursky@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>