MapQuest improvement (#840)

* Changes to common files for PR #840

* MapQuest support 5Box address specification

* With these changes I find it way easier to merge your PR

* Let us keep the method extractAddressFromQuery

* Update Readme.md

Author: TerjeBr

GetAddressInterface.php

@@ -0,0 +1,21 @@
+<?php
+
+/*
+ * This file is part of the Geocoder package.
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ *
+ * @license    MIT License
+ */
+
+namespace Geocoder\Provider\MapQuest;
+
+use Geocoder\Location;
+
+interface GetAddressInterface
+{
+    /**
+     * @return Location|null
+     */
+    public function getAddress();
+}