react-datetime Add a defaultTime prop

I'm Submitting a ...

[ ] Bug report
[x] Feature request
[ ] Support request

Steps to Reproduce

Add a defaultTime prop to the element

<ReactDateTime
  dateFormat="YYYY-MM-DD"
  timeFormat="HH:mm:ss"
  defaultTime="23:59:59"
/>

Expected Results

When clicking on a day in the calendar, if defaultTime is set, the datetime obtained should show the provided default time (in my example above: "23:59:59") instead of "00:00:00" as it currently does

Actual Results

Nothing, hence the feature request

Why?

I am using this component to make a DateTime range picker and I'd like the default times to be "00:00:00" for the "From" input, but "23:59:59" for the "To" input, yet I need the defaultValue to be undefined since I want to support open-ended ranges. Such a new feature would make this use-case really easy:

<label>FROM:</label>
<ReactDateTime
  dateFormat="YYYY-MM-DD"
  timeFormat="HH:mm:ss"
/>

<label>TO</label>
<ReactDateTime
  dateFormat="YYYY-MM-DD"
  timeFormat="HH:mm:ss"
  defaultTime="23:59:59"
/>