package/dnsmasq: permit UCI configuration of --dhcp-fqdn option

This adds a new boolean option, fqdn, to the "config dnsmasq" section of
/etc/config/dhcp. The default is off. When set on, it enables the dhcp-fqdn
option to dnsmasq. dhcp-fqdn causes dnsmasq's DNS server to not resolve
unqualifed local hostnames. The "domain" option is required when using "fqdn".
Local hostnames will remain available for lookup using fully-qualified names.

Signed-off-by: Mark Mentovai <mark@moxienet.com>

SVN-Revision: 32569