Merged in feature/from-pantheon (pull request #16)

code from pantheon

* code from pantheon

wp/wp-content/plugins/wordpress-seo/src/exceptions/indexable/post-not-found-exception.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Yoast\WP\SEO\Exceptions\Indexable;
+
+/**
+ * Exception that is thrown whenever a post could not be found
+ * in the context of the indexables.
+ */
+class Post_Not_Found_Exception extends Source_Exception {
+
+	/**
+	 * Exception that is thrown whenever a post could not be found
+	 * in the context of the indexables.
+	 */
+	public function __construct() {
+		parent::__construct( \__( 'The post could not be found.', 'wordpress-seo' ) );
+	}
+}