解决启用 codemirror后，jquery获取不到textarea 的值

例子

 <textarea id="config" name="config"  class="form-control"></textarea>

 window.editor_two = CodeMirror.fromTextArea(document.getElementById("config"), {
                            lineNumbers: true,
                            matchBrackets: true,
                            styleActiveLine: true
                        });

 var d = {'config': editor_two.getValue() };