添加增量编译支持

[chenfei0928]

as 3.5 之后，as引入了注释处理器增量编译api支持，可以增加编译速度
BGABadge在这个版本下编译出现了以下警告

w: [kapt] Incremental annotation processing requested, but support is disabled because the following processors are not incremental: cn.bingoogolapple.badgeview.compiler.BGABadgeProcessor (NON_INCREMENTAL).

[runforprogram]

#74