Improve highlights animation on home page

[caprica]

The intent of the highlights animation on the home page is to replay the animation each time the highlights change.

This was attempted in #32 making use of a "key" attribute on the outer animation.

This appeared to work.

However, after time and perhaps tab off then tab on, or some race with the highlights data request, the animation glitches out and the outer animation stays with opacity 0 and hence no highlights shown.

The PR was therefore reverted.

[caprica]

After testing another fix with a slightly different implementation, eventually the same glitched condition came back again, so that attempt too was reverted.

See: #73