The network management module of an energy management system for Android phones

1. Modify the target SDK version as 19 (Android 4.4.2) and the minimum SDK version as 15 (Android 4.0.3)
2. Change source code encoding from GBK to UTF-8.
3. Translate comments into English.
4. Fix warnings: modify expressions of changing data types.

Copyright (c) 2014 Tianwei Liu. See the LICENSE file for license rights and limitations (MIT).