fix:修复通话记录不显示添加工单按钮问题

WebUI/CallCenterWeb.UI/TelCall/CallRecord.html

         //格式化工单号
         function formatWorkOrderNum(val, row) { 
         	if (row.CallType ===0) {
-        		if (val == null) {
+        		if (val == null || val == '') {
 	               return '<a class="xg" onclick="addWorkOrder(\'' + row.CallRecordsId  + '\',\'' +row.CallNumber+'\')" title="添加工单">添加工单</a>';
 	            } else {
 	                return '<a class="xg" onclick="ckxq(\'' + val + '\')" title="点击查看工单详情">' + val + '</a>';