[rating-bar] adds hover event

Author: LaercioSantana

docs/src/pages/components/RatingBar.vue

@@ -88,6 +88,11 @@
                 <md-table-cell>Receive the new rating</md-table-cell>
                 <md-table-cell>Triggered when the rating changes his value by user interaction.</md-table-cell>
               </md-table-row>
+              <md-table-row>
+                <md-table-cell>hover</md-table-cell>
+                <md-table-cell>Receive the pointer rating</md-table-cell>
+                <md-table-cell>Triggered when the user points over a new rating.</md-table-cell>
+              </md-table-row>
             </md-table-body>
           </md-table>
         </api-table>

src/components/mdRatingBar/mdRatingBar.vue

@@ -131,6 +131,7 @@
       hoverStars(evt) {
         if (!this.disabled) {
           this.rating = this.getIconIndex(evt.currentTarget);
+          this.$emit('hover', this.rating);
         }
       },
       clickStars(evt) {