added API settings endpoints

Author: flowdee

src/Api/Settings.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace MailerLiteApi\Api;
+
+use MailerLiteApi\Common\ApiAbstract;
+
+class Settings extends ApiAbstract {
+
+    protected $endpoint = 'settings';
+
+    /**
+     * Retrieve double opt in status
+     *
+     * @return mixed
+     */
+    public function getDoubleOptin()
+    {
+        $endpoint = $this->endpoint . '/double_optin';
+
+        $response = $this->restClient->get( $endpoint );
+
+        return $response['body'];
+    }
+
+    public function setDoubleOptin( $status ) {
+
+        $endpoint = $this->endpoint . '/double_optin';
+
+        $params = array_merge($this->prepareParams(), ['enable' => $status] );
+
+        $response = $this->restClient->post( $endpoint, $params );
+
+        return $response['body'];
+    }
+
+}

src/MailerLite.php

@@ -81,6 +81,14 @@ public function stats()
         return new \MailerLiteApi\Api\Stats($this->restClient);
     }
 
+    /**
+     * @return \MailerLiteApi\Api\Settings
+     */
+    public function settings()
+    {
+        return new \MailerLiteApi\Api\Settings($this->restClient);
+    }
+
     /**
      * @param  string $version
      * @return string