Default to 00:00 time when picking other days but today

[sabbaka]

When we are choosing anything but today's date, when time picker window opens, it should be reset to 00:00:00. It doesn't make sense offering the default of current time if we're choosing another day.

[spbnick]

At the moment the date-time picker we use loads the default of page load time and suggests its hours and minutes, even when we are choosing another day. It should reset these to zeros.

[spbnick]

Ideally, the picker should be fixed upstream.