add logs readme

+## logs
+logs is a Go logs manager. It can use many logs adapters. The repo is inspired by `database/sql` .
+
+
+## How to install?
+
+	go get github.com/astaxie/beego/logs
+
+
+## What adapters are supported?
+
+As of now this logs support console, file,smtp and conn.
+
+
+## How to use it?
+
+First you must import it
+
+	import (
+		"github.com/astaxie/beego/logs"
+	)
+
+Then init a Log (example with console adapter)
+
+	log := NewLogger(10000)
+	log.SetLogger("console", "")	
+
+> the first params stand for how many channel
+
+Use it like this:	
+	
+	log.Trace("trace")
+	log.Info("info")
+	log.Warn("warning")
+	log.Debug("debug")
+	log.Critical("critical")
+
+
+## File adapter
+
+Configure file adapter like this:
+
+	log := NewLogger(10000)
+	log.SetLogger("file", `{"filename":"test.log"}`)
+
+
+## Conn adapter
+
+Configure like this:
+
+	log := NewLogger(1000)
+	log.SetLogger("conn", `{"net":"tcp","addr":":7020"}`)
+	log.Info("info")
+
+
+## Smtp adapter
+
+Configure like this:
+
+	log := NewLogger(10000)
+	log.SetLogger("smtp", `{"username":"beegotest@gmail.com","password":"xxxxxxxx","host":"smtp.gmail.com:587","sendTos":["xiemengjun@gmail.com"]}`)
+	log.Critical("sendmail critical")
+	time.Sleep(time.Second * 30)