Deal with settings read/write errors properly

app/Settings/WriteException.php

@@ -0,0 +1,34 @@
+<?php
+
+/*
+ * This file is part of Cachet.
+ *
+ * (c) Alt Three Services Limited
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace CachetHQ\Cachet\Settings;
+
+use Exception;
+
+/**
+ * This is the write exception class.
+ *
+ * @author Graham Campbell <graham@alt-three.com>
+ */
+class WriteException extends SettingsException
+{
+    /**
+     * Create a new write exception instance.
+     *
+     * @param \Exception $e
+     *
+     * @return void
+     */
+    public function __construct(Exception $e)
+    {
+        parent::__construct('Unable to write Cachet settings', $e);
+    }
+}