time-field: no seconds, no switch for 24h format

For component TimeField even when parameter
showSeconds=true
only hour and minute are shown/changeable.

Fix could be in fields/time-field.js
<TimePicker
...
ampm=.....
views={ showSeconds?['hours','minutes','seconds']:['hours','minutes'] }
...
/>

To get a fixed 24h display an additional parameter for ampm is required?

Similar issue for DateField when includeTime=true

[redgeoff]

On the surface this seems like a bug or a missing feature. Let me find some time to take a look...