nsinit: Add Makefile

Signed-off-by: Andrey Vagin <avagin@openvz.org>
nsinit: exec
libct: start a process
nsinit: add ct.RunState
Dockerfile: compile libct
Add namespaces/types to include it in libcontainer
libct: ct.SetNsMask
libct: set parent death signal
libct: set capabilities
go fmt