Fix invalid volatile long/int increment (++)

The findbugs complains about incrementing a volatile variable in AuthFastLeaderElection and FastLeaderElection:

volatile long logicalclock; /* Election instance */
...
logicalclock++;

Actually this is a bug. It should use AtomicLong here instead of volatile.

Leader.java and QuorumPeer.java and LearnerHandler.java:

volatile int tick;

I don't think it needs volatile here. The tick is incremented only in Leader.java:

  synchronized (this) {
          ...
                    if (!tickSkip) {
                        self.tick++;
                    }
  }

and it's protected by the synchronized statement. I just remove volatile keyword.