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)
Merge pull request #9107 from ashahab-altiscale/9062-linked-container

Share network namespace of containers with lxc