libcontainer: move Config in a separate package

We are going to import the namespaces package into libcontainer,
so libcontainer should not be imported into namespaces.

Signed-off-by: Andrey Vagin <avagin@openvz.org>
libcontainer: move State in the configs package

We are going to import the namespaces package into libcontainer,
so libcontainer should not be imported into namespaces.

Signed-off-by: Andrey Vagin <avagin@openvz.org>
nsinit: clean up

Signed-off-by: Andrey Vagin <avagin@openvz.org>
linux_container: create container

Signed-off-by: Andrey Vagin <avagin@openvz.org>
libcontainer: optimize updateStateFile()

Signed-off-by: Andrey Vagin <avagin@openvz.org>
libcontinaer: use new API in integration tests
process: use io.Reader instead of io.WriteCloser for standard fds