Add support for child components

[glan]

Allows child components to be added to the end of the component.

<DateTimePicker>
  <DurationSelect/>
</DateTimePicker>

[chollier]

Hi @glan,

I'm not super inclined to have children passed to the picker. Why wouldn't you put the DurationSelect just after ?

<DateTimePicker /><DurationSelect />

[glan]

@chollier It's because I'm wanting to share the same input-group. Since calendar button is of type input-group-addon it permits adding additional add ons such as input-group-btn.

[glan]

Like this: http://getbootstrap.com/components/#input-groups-buttons-segmented