lxc-ls: prepend container name with -- when calling ls
lxc-ls: prepend container name with -- when calling ls

Otherwise a container name with a dash confuses ls

Signed-off-by: Serge Hallyn <3df611b026e4639bee8aef7a4beb2e39fcebb313@ubuntu.com>

ostap/lxc,ostap/lxc