获取路由配置格式不对，解析异常

[lizhi1314]

Describe the bug
从git拉的最新版本打的包，cat-client版本为3.1.0，部署启动正常，能正常打开后台，但是客户端日志有异常，显示从服务端获取的数据无法解析。

[01-03 16:47:31.538] [ERROR] [TcpSocketSender] error when connect cat server config url http://127.0.0.1:8080/cat/s/router?domain=lab&ip=192.168.0.106&op=xml&env=unknown&hostname=MacBook-Pro.local
org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; 前言中不允许有内容。
at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:204)
at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.fatalError(ErrorHandlerWrapper.java:178)
at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:400)
at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:327)
at com.sun.org.apache.xerces.internal.impl.XMLScanner.reportFatalError(XMLScanner.java:1467)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:1009)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:605)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:507)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:867)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:796)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:142)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1216)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:644)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl.parse(SAXParserImpl.java:328)
at com.dianping.cat.configuration.property.transform.DefaultSaxParser.parseEntity(DefaultSaxParser.java:58)
at com.dianping.cat.configuration.property.transform.DefaultSaxParser.parse(DefaultSaxParser.java:29)
at com.dianping.cat.configuration.property.transform.DefaultSaxParser.parse(DefaultSaxParser.java:41)
at com.dianping.cat.configuration.DefaultClientConfigService.refreshConfig(DefaultClientConfigService.java:220)
at com.dianping.cat.configuration.DefaultClientConfigService.refreshConfig(DefaultClientConfigService.java:186)
at com.dianping.cat.configuration.DefaultClientConfigService.getRouters(DefaultClientConfigService.java:124)
at com.dianping.cat.message.io.ChannelManager.routerConfigChanged(ChannelManager.java:354)
at com.dianping.cat.message.io.ChannelManager.checkServerChanged(ChannelManager.java:143)
at com.dianping.cat.message.io.ChannelManager.run(ChannelManager.java:372)
at java.lang.Thread.run(Thread.java:750)

直接访问接口访问：172.27.232.42:2280;

很明显返回的不是xml格式，解析肯定抛异常，但是这是最新的代码，有bug的代码也提交上来？