Shows 5 star rating or enables a 5 star rating vote using paper-icon-button and iron-icon.
<star-rating rate="4"></star-rating>
<star-rating rate="2.3"></star-rating>
<star-rating rate="3.6"></star-rating>
<star-rating rate="2" read-only>
<div votes>
  (12
votes)
</div>
</star-rating>
<star-rating rate="1" read-only>
<div votes>
  10
votes
</div>
</star-rating>