Allow the id-as-number issue for tree view nodes.

Author: grapoza

package.json

@@ -3,7 +3,7 @@
   "description": "Yet another Vue treeview component.",
   "author": "Gregg Rapoza <grapoza@gmail.com>",
   "license": "MIT",
-  "version": "0.3.1",
+  "version": "0.3.2",
   "browser": "vue-tree.umd.min.js",
   "repository": {
     "url": "https://github.com/grapoza/vue-tree",

src/components/TreeView.vue

@@ -40,8 +40,7 @@
       };
     },
     mounted() {
-      // Force the uniqueId to be a string if present
-      this.$set(this, 'uniqueId', this.$el.id ? this.$el.id + '' : null);
+      this.$set(this, 'uniqueId', this.$el.id ? this.$el.id : null);
     },
     methods: {
       getCheckedCheckboxes() {

src/components/TreeViewNode.vue

@@ -99,7 +99,7 @@
         required: true
       },
       parentId: {
-        type: String,
+        type: [String, Number],
         required: false
       },
       treeId: {