修复上传文件时当文件临时id为0的情况

vendor/iron/widgets/Upload.php

@@ -198,7 +198,7 @@ class Upload extends InputWidget
                     success: function(data)
                     {
                             var imageval = $('#{$this->fillInId}').val();
-                            if(imageval == ''){
+                            if(imageval == '' || imageval == 0){
                                 $('#{$this->fillInId}').val(data);
                             }else{
                                 $('#{$this->fillInId}').val($('#{$this->fillInId}').val()+','+data);