Possible issue with waiting to catch up to master position's connection getting closed? #49

As we merged #35, I moved the code that initialized the initializeWaitUntilReplicaIsCaughtUpToMasterConnection call in ShardingFerry from after Waiting for binlog to catchup to Initialize, which is quite a big change. The reason to do is is such that Ferry could use the WaitUntilReplicaIsCaughtUpToMaster struct to sanity check the configuration during the Initialize phase.

A comment on the PR says that the reason of the previous placement is because pt-kill will kill idle connections. If we connect to the master too early (during Initialize), the connection might no longer be available. It was under my impression that the Go driver will handle this transparently.

Since, we never resolved that comment, I'm moving the discussion out here.

cc: @hkdsun @pushrax