master, client: send stdout and stderr from slave to client

Signed-off-by: Paweł Dziepak <pdziepak@quarnos.org>
process: fix get_stdout()

Signed-off-by: Paweł Dziepak <pdziepak@quarnos.org>
client: do not append ' ' at the end of command line

Signed-off-by: Paweł Dziepak <pdziepak@quarnos.org>