Change namespaces config to include path for setns

This changes the namespace configuration on the config to include the
name of the namespace along with an optional path.  This path is used to
point to a file of another namespace for the namespace so that it can be
joined in place of the empty, initialized namespace.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Remove unused namespace types

This removes the unsued namespace types from the namespace package
and simplifies getting the values for the namespaces.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Merge pull request #279 from crosbymichael/namespaces-join

Change namespaces config to include path for setns
cgroups: add support for cpuset.mems

Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Merge pull request #285 from hqhq/hq_add_cpuset_mems

cgroups: add support for cpuset.mems
Merge pull request #3 from docker/master

Merge upstream