Use consumer fd reference in consumer socket obj

Use consumer fd reference in consumer socket obj

This is done so we don't copy the fd value of the consumer thus having a
central control. This is part of a set of patches that makes the session
daemon stop sending command to an invalid consumer (dead, closed).

Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: David Goulet <dgoulet@efficios.com>