* speedup ActorCreationPerfSpec
* reduce iterations in ConsistencySpec
* tag SupervisorHierarchySpec as LongRunningTest
* various small speedups and tagging in actor-tests
* speedup expectNoMsg in stream-tests
* tag FramingSpec, and reduce iterations
* speedup QueueSourceSpec
* tag some stream-tests
* reduce iterations in persistence.PerformanceSpec
* reduce iterations in some cluster perf tests
* tag RemoteWatcherSpec
* tag InterpreterStressSpec
* remove LongRunning from ClusterConsistentHashingRouterSpec
* sys property to disable multi-jvm tests in test
* actually disable multi-node tests in validatePullRequest
* doc sbt flags in CONTRIBUTING
* Sink.queue and Sink.actorRefWithAck can now handle one element input
buffers
* Sink.queue now buffers as much upstream elements as declared in its
InputBuffer attribute, instead of one less.
* Tests for streaming with full buffer now do not depend on default
input buffer size (16); instead, they set sink input buffer size
explicitly.
* Sink.{queue, actorRefWithAck} and StreamConverters.{asInputStream,
asOutputStream} now use overriden/inherited `InputBuffer` attribute
* They now use their default attributes as initial attributes.
