Revert "lib: Remove form element `Note'"

This reverts commit c21d7d1fdda460050cac822e5627fd584b3f7a01.

library/Icinga/Web/Form/Element/Note.php

@@ -0,0 +1,31 @@
+<?php
+// {{{ICINGA_LICENSE_HEADER}}}
+// {{{ICINGA_LICENSE_HEADER}}}
+
+namespace Icinga\Web\Form\Element;
+
+use Zend_Form_Element_Xhtml;
+
+/**
+ * Implements note element for Zend forms
+ */
+class Note extends Zend_Form_Element_Xhtml
+{
+    /**
+     * Name of the view helper
+     *
+     * @var string
+     */
+    public $helper = 'formNote';
+
+    /**
+     * Return true to ensure redrawing
+     *
+     * @param mixed $value      The value of to validate (ignored)
+     * @return bool             Always true
+     */
+    public function isValid($value)
+    {
+        return true;
+    }
+}