Update layer when time slider is clicked

The map would update if the animation slider was dragged but not if a
new position was set by clicking on the slider. This addresses that by
listening to the changecomplete event, there may be a more appropriate
event to listen to but I could not find it, I tried dragend for example.
Whitespace changes
Merge pull request #708 from aodn/time-step-slider-click

Update layer when time slider is clicked