gradle构建

参考

• http://www.cnblogs.com/gzdaijie/category/798374.html
• http://mp.weixin.qq.com/s?__biz=MzIzMjE1Njg4Mw==&mid=2650117738&idx=1&sn=cfaf39a23d9ebe655f687e4abb90312c#rd
• http://www.figotan.org/2016/04/01/gradle-on-android-best-practise/
• http://blog.csdn.net/Innost/article/details/48228651