feature:支持使用配置文件，增加网络检查

1、从Config.json读取配置
2、网络正常时跳过登录

Util/file.go

@@ -0,0 +1,39 @@
+package Util
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"os"
+)
+
+type file struct {
+}
+
+var File file
+
+func (*file) Exists(path string) bool {
+	_, err := os.Stat(path)
+	if err != nil {
+		if os.IsExist(err) {
+			return true
+		}
+		return false
+	}
+	return true
+}
+
+func (*file) Read(path string, receiver interface{}) error {
+	file, err := ioutil.ReadFile(path)
+	if err != nil {
+		return err
+	}
+	return json.Unmarshal(file, receiver)
+}
+
+func (*file) Write(path string, receiver interface{}) error {
+	data, err := json.MarshalIndent(receiver, "", " ")
+	if err != nil {
+		return err
+	}
+	return ioutil.WriteFile(path, data, 777)
+}