with this patch,container's meminfo will be shown based on
containers' mem cgroup.

Right now,it's impossible to virtualize all values in meminfo,
I collect some values such as MemTotal,MemFree,Cached,Active,
Inactive,Active(anon),Inactive(anon),Active(file),Inactive(anon),
Active(file),Inactive(file),Unevictable,SwapTotal,SwapFree.

if I miss something, please let me know.
Signed-off-by: NGao feng <gaofeng@cn.fujitsu.com>