feat: Add Component#getId, Component#getNode

Getter method for Component#_requestingUpdate has deliberately not been
added. Component#requestUpdate should be sufficient to hook into the
node's update cycle.

core/Component.js

@@ -114,4 +114,23 @@ Component.prototype.onUpdate = function onUpdate () {
     this._requestingUpdate = false;
 };
 
+/**
+ * @method
+ *
+ * @return {Node}       Node to which the component has been added.
+ */
+Component.prototype.getNode = function getNode() {
+    return this._node;
+};
+
+/**
+ * @method
+ *
+ * @return {Number}     Id assigned by the Node when the component has been
+ *                      added.
+ */
+Component.prototype.getId = function getId() {
+    return this._id;
+};
+
 module.exports = Component;