fix bug in pink: set in_conn = NULL before every event for lop, or it may delete last valid in_conn in conns_ when both EPOLLHUB and EPOLLERR happend

1, add connect wait state\n2, clear target rsync dir after rsync send\n3, add master ipport into module name

2) update pink with in_conn with invalid value;
3) initilize bgsaving_engine.