Add concurrency torture test for Skiis.merge()
remove(t) should only remove one element
Don't throw exception in Ring.remove(); breaks tests
Eliminate synchronization bottleneck in FlatMapOp
Merge branch 'master' into bizo-2.10

* master:
  Eliminate synchronization bottleneck in FlatMapOp
  Don't throw exception in Ring.remove(); breaks tests
  remove(t) should only remove one element
  Add concurrency torture test for Skiis.merge()
Remove build.properties
Ignore build.properties