mainline: improved SocketContext initializing interface
mainline: improved SocketContext initializing interface

kerryjiang/SuperSocket,ZixiangBoy/SuperSocket,mdavid/SuperSocket,mdavid/SuperSocket,ZixiangBoy/SuperSocket,fryderykhuang/SuperSocket,fryderykhuang/SuperSocket,chucklu/SuperSocket,ZixiangBoy/SuperSocket,jmptrader/SuperSocket,jmptrader/SuperSocket,mdavid/SuperSocket,jmptrader/SuperSocket,memleaks/SuperSocket,kerryjiang/SuperSocket,chucklu/SuperSocket,chucklu/SuperSocket,fryderykhuang/SuperSocket