LINKED CONTAINER ID PASSED TO LXC

This passed the --net=container:CONTINER_ID to lxc-start as --share-net
Docker-DCO-1.1-Signed-off-by: Abin Shahab <ashahab@altiscale.com> (github: ashahab-altiscale)

Fixes #9062

Tested on centos 6.5 with lxc 1.0.6