Add option 'scriptarp' to uci dnsmasq config to enable --script-arp functions.
The default setting is false, meaning any scripts in `/etc/hotplug.d/neigh` intended
to be triggered by `/usr/lib/dnsmasq/dhcp-script.sh` will fail to execute.
Also enable --script-arp if has_handlers returns true.
Signed-off-by: Jordan Sokolic <oofnik@gmail.com>
Signed-off-by: Hans Dedecker <dedeckeh@gmail.com> [PKG_RELEASE increase]