cgroup::ControlGroup thread-safety description.
cgroup::ControlGroup naming fix.
cgroup::ControlGroup {attach,create}Child() and parent() implementation.
cgroup::SingleControlGroup refactoring.
cgroup::Error::controlGroupPath declaration.
cgroup::SingleControlGroup: hierarchy traversal partial implementation.

~SingleControlGroup(), attachChild(), createChild(), root() and attach() implementation.
attachDirectChild() and createDirectChild() declaration.
cgroup::SingleControlGroup: attachDirectChild() and createDirectChild() partial implementation.