Run dnsmasq with options --keep-in-foreground and --pid-file.

Tell dnsmasq to run with option --keep-in-foreground instead
of --no-daemon, which is meant for debug purposes only. Also
use option --pid-file to tell dnsmasq not use a pid file.

Change-Id: I82858d911e94407b2511d8ce8388be553f2f09f6