applications/luci-dump1090: fix disabling service instance

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
applications/luci-udpxy: fix disabling service instance

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
applications/luci-shairplay: fix disabling service instance

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
applications/luci-shairport: fix disabling service instance

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Merge pull request #250 from openwrt-es/luci-next2

Fix disabling service instance for dump1090/udpxy/shairplay/shairport