[TACHYON-163]After 5 attempts we exit to avoid infinity retires

https://tachyon.atlassian.net/browse/TACHYON-163

Probably we should exit after attempts
If the connect method leads to infinity loop, user might think TahcyonWorker is fine with seeing the JVM process still existing.
I see your point. Maybe we'd better not exit here as worker will register as master requests.
But I'm not clear in which scenario master will request worker to reregister ( in code it is when master couldn't find value of `workerId` in `MasterInfo.mWorkers`).