add migration file

src/application/migrations/001_specific_calendar_sync.php

@@ -0,0 +1,25 @@
+<?php defined('BASEPATH') OR exit('No direct script access allowed');
+
+class Migration_Specific_calendar_sync extends CI_Migration {
+
+	public function up() {
+		$fields = array(
+			'google_calendar' => array(
+				'type' => 'VARCHAR',
+				'constraint' => '128',
+				'default' => 'null')
+		);
+		
+		$this->dbforge->add_column('ea_user_settings', $fields);
+	}
+
+	public function down() {
+		$this->dbforge->drop_column('ea_user_settings', 'google_calendar');
+	}
+}
+
+/*
+ * This migration class adds the "google_calendar" field to the database 
+ * "user_settings" table in order to be able to select a specific calendar 
+ * for google synchronization. 
+ */