[JDK8] Replace use of high-scale-lib counters with intrinsic facilities

JEP155 introduces a few new classes (DoubleAccumulator, DoubleAdder, LongAccumulator, LongAdder) that "internally employ contention-reduction techniques that provide huge throughput improvements as compared to Atomic variables". There are applications of these where we are currently using Cliff Click's high-scale-lib and for metrics.

See http://openjdk.java.net/jeps/155