add httplib readme

+# httplib
+httplib is an libs help you to curl remote url.
+
+# How to use?
+
+## GET
+you can use Get to crawl data.
+
+	import "httplib"
+	
+	str, err := httplib.Get("http://beego.me/").String()
+	if err != nil {
+		t.Fatal(err)
+	}
+	fmt.Println(str)
+	
+## POST
+POST data to remote url
+
+	b:=httplib.Post("http://beego.me/")
+	b.Param("username","astaxie")
+	b.Param("password","123456")
+	str, err := b.String()
+	if err != nil {
+		t.Fatal(err)
+	}
+	fmt.Println(str)
+
+## set timeout
+you can set timeout in request.default is 60 seconds.
+
+set Get timeout:
+
+	httplib.Get("http://beego.me/").SetTimeout(100 * time.Second, 30 * time.Second)
+	
+set post timeout:	
+	
+	httplib.Post("http://beego.me/").SetTimeout(100 * time.Second, 30 * time.Second)
+
+- first param is connectTimeout.
+- second param is readWriteTimeout
+
+## debug
+if you want to debug the request info, set the debug on
+
+	httplib.Get("").Debug(true)
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