issue-650 DynamicLoadBalancingPolicy: LatencyAwareHClientPool may thr…

…ow NoSuchElementException under certain circumstances

Using the poll() method of the LinkedBlockingDeque prevent
NoSuchElementException throwing in case the deque is cleared by the
DynamicLoadBalancingPolicy resetThread.

core/src/main/java/me/prettyprint/cassandra/connection/LatencyAwareHClientPool.java

@@ -45,7 +45,7 @@ void add(double i) {
     if (intervalupdates.intValue() >= UPDATES_PER_INTERVAL)
       return;
     if (!latencies.offer(i)) {
-      latencies.remove();
+      latencies.poll();
       latencies.offer(i);
     }
     intervalupdates.getAndIncrement();