lxc-config can show lxc.cgroup.(use|pattern)

Signed-off-by: KATOH Yasufumi <karma@jazz.email.ne.jp>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
lxc_global_config_value can return the default lxc.cgroup.pattern whether root or non-root

>>> On Tue, 30 Sep 2014 19:48:09 +0000
    in message   "Re: [lxc-devel] [PATCH] lxc-config can show lxc.cgroup.(use|pattern)"
                  Serge Hallyn-san wrote:

> I think it would be worth also augmenting
> lxc_global_config_value() to return a default lxc.cgroup.use
> for 'all', and a default lxc.cgroup.pattern ("/lxc/%n" for root
> or "%n" for non-root).

lxc.cgroup.pattern is like this? (^_^;)

Signed-off-by: KATOH Yasufumi <karma@jazz.email.ne.jp>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>