DateTime UI module: removed ntp-server system validator. Refs #1988
/etc/ntp.conf template: use upstream defaults with expanded ntpd/NTPServer prop value. Refs #1988
/etc/ntp/step-tickers template: removed, because ntpdate is deprecated. Refs #1988
DateTime UI module template: time controls enabled only if ntpd is not running; fixed translations. Refs #1988
DateTime UI module: refresh time visualization every minute. Refs #1988
Release 1.0.3