luci-app-ddns: update/rebuild to support ddns-scripts V 2.x

extends/replaces exising luci-app-ddns to support ddns-scripts starting
Version 2.0.1-8
Still supports ddns-scripts Version 1.0.0-23 with the old interface
including fix for OpenWrt Ticket #18018.

Signed-off-by: Christian Schoenebeck <christian.schoenebeck@gmail.com>
Merge pull request #223 from chris5560/master

luci-app-ddns: update/rebuild to support ddns-scripts V 2.x