Add favorite-button.

src/components/favorite_button/favorite_button.js

@@ -0,0 +1,22 @@
+const FavoriteButton = {
+  props: [ 'status' ],
+  methods: {
+    favorite () {
+      if (!this.status.favorited) {
+        this.$store.dispatch('favorite', { id: this.status.id})
+      } else {
+        this.$store.dispatch('unfavorite', { id: this.status.id})
+      }
+    }
+  },
+  computed: {
+    classes () {
+      return {
+        'icon-star-empty': !this.status.favorited,
+        'icon-star': this.status.favorited
+      }
+    }
+  }
+}
+
+export default FavoriteButton