Send data at specific interval of time

[Colin]

@dceejay

the default inject node can also mange to handle every 15 minutes

There is an ongoing issue with that node (unless it has been sorted) that if the system time changes after node red has started that it loses sync as it does not notice that the clock has changed. This can easily happen on boot on something like a pi with wifi if node red starts up before the wifi gets going, so the first time sync happens after the inject node has started up. There was discussion of it here, but I don't know whether an issue got raised.