Rewrite the gluon-wan-dnsmasq initfile to use procd. This allows for
configuring restart handling by procd in case of a crash.

While at it, disable the caching feature optionally used for the regular
dnsmasq on the wan dnsmasq. This daemon is only for redirecting DNS
requests to use local network resolvers, not introducing caching.

Signed-off-by: David Bauer <mail@david-bauer.net>