Per #322 update AtomicCounter and AtomicCounterLong with thread-safety fixes and move to Akka.Util.Internal. Remove AtomicInteger/AtomicLong.
Sync AtomicCounterLong to AtomicCounter internally.
Merge pull request #335 from mattnischan/atomiccounters

Per #322 update AtomicCounter and AtomicCounterLong with thread-safety f...