日志 logs
基于xml配置的日志系统。兼容标准库的log.Logger。
```xml
<?xml version="1.0" encoding="utf-8" ?>
<logs>
<debug>
<buffer size="10">
<rotate dir="/var/log/" size="5M" />
<stmp username=".." password=".." />
</buffer>
</debug>
<info>
....
</info>
</logs>
```
```go
logs.InitFromXMLFile("./config.xml")// 用xml初始化logs
logs.Debug("debug start...")
logs.Debugf("%v start...", "debug")
logs.DEBUG.Println("debug start...")
```
