luna-init: defaultPreferences.txt add timeSources key.
luna-init: defaultPreferences.txt add timeSources key.

Fixes:
Oct 25 11:30:45 qemux86 LunaSysService[476]: [] [pmlog] LunaSysService INVALID_JSON {"MSGID":"MISSING_PREF_TIMESOURCES", "CAUSE":"The json string is wrong.","JSON":"{\"HARDCODED\":\"[\"ntp\",\"sdp\",\"nitz\",\"broadcast-adjusted\",\"broadcast\"]\"} No timeSources preference defined falling back to hard-co ..."}

Signed-off-by: Herman van Hazendonk <c2208abde9668e8e9815c3690855edd1e63abeac@herrie.org>

webOS-ports/luna-init