speed container creation/destruction

speed container creation/destruction

As the state of the container is monitored with the netlink,
the file state is no longer used to watch the state changes.

The previous hack, which adds a tempo of 200ms, is removed and
that makes the container being created, started, stopped, destroyed
faster, we gain 1 second in a container lifecycle. One second is
too much if we launch thousand of containers, one by one like for
example in a tests suite.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>