This gives me an uneasy feeling.  This process flag is being applied to the caller of `start_link` which in this case happens to be Yokozuna's application master.  I'm not so sure we should be playing process flag games with a process we don't own.

Furthermore, I noticed this seems to cause issues when stoping.  I don't think it's caused by this PR.  Rather when calling stop the `yz_events` server gets a gen_event exit from riak_core_ring_events which it doesn't seem to have a handle_info for and thus causes a function clause error to get thrown.  This in turn trips the trap exit and the "Yokozuna had a problem starting..." message.

OH...wow, yea this is bad.  This call is never returning because of the receive call below.  It's blocking because this receive call is executing on application master process.  That process, in turn, doesn't wait for a message from the application it's starting, the app start is synchronous.  So the only thing that is going to trip this receive is a) a crash or b) some other message that might be sent to application master but that is OTP land and nothing we should touch.  Thus just dropping the message like we do below could have other unintended consequences.