fix up nstar to not depend on system's getpwuid()

also add some error-handling and fix up directory creation permissions

Signed-off-by: Simon Leung <leungs@us.ibm.com>
fix to pass username to nstar

Signed-off-by: Simon Leung <leungs@us.ibm.com>
declare setns manually as no header provides it

man page says sched.h, but importing that doesn't fix it

Signed-off-by: Simon Leung <leungs@us.ibm.com>
tests now work with a busybox test image

Signed-off-by: Simon Leung <leungs@us.ibm.com>
use nstar for StreamOut as well

Signed-off-by: Simon Leung <leungs@us.ibm.com>
A running docker-image based app should have container-defined environment variables *in addition* to the standard CF environment variables
[#75752312]