Convert entered timestamps to ISO 8601

[rgov]

@cgraver requests:

When entering or tweaking times in "Milestones/Stats" to populate things like "lowering_on_bottom" in the *loweringRecord.json file, if the system or calendar is used to enter the time, the time record is produced in ISO format yyyy-mm-ddThh:mm:ss.sssZ. When entered manually, it often gets entered as yyyy-mm-dd hh:mm or yyyy/mm/dd hh:mm. Is it possible to have the times, if entered in these other formats, automatically convert to show up in the interface and *loweringRecord.json as ISO format?

[webbpinner]

Had a similar issue a while back. added value={input.value ? moment.utc(input.value).format(dateFormat + ' ' + timeFormat) : null} to <Datetime> definition in form_elements.js. Might help. Source