net: tools: Helper scripts for running socat, tunslip6 and radvd

Adding convenience scripts that help user when running socat,
radvd and tunslip6 processes. These helper scripts restart
corresponding processes when qemu stops. This way end user
does not need to manual restart the utility processes.

Change-Id: I2e8eb15ee0ffe2ac8f1cedf4431cf8b09fcbbee5
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>