LXC CAP ADD CAP DROP IN TEMPLATE

Added cap-drop and cap-add in lxc template
Docker-DCO-1.1-Signed-off-by: Abin Shahab <ashahab@altiscale.com> (github: ashahab-altiscale)
Merge pull request #9447 from ashahab-altiscale/7687-lxc-cap-add-cap-drop

LXC CAP ADD CAP DROP IN TEMPLATE