更新了readme，添加了gradle构建的方式
更新了readme，添加了gradle构建的方式

Heart2009/ExRecyclerView,sahilk2579/ExRecyclerView,canmeidanxue/ExRecycle,yanhaogoogle/ExRecyclerView,lgx0955/ExRecyclerView,pitatensai/ExRecyclerView,0359xiaodong/ExRecyclerView,xujianhai/ExRecyclerView,clg0118/ExRecyclerView