refactored AbstractCompositeStage (name and non-abstract)

src/main/java/teetime/framework/AbstractStage.java

src/main/java/teetime/framework/CompositeStage.java

src/main/java/teetime/framework/Configuration.java

src/main/java/teetime/stage/io/EveryXthPrinter.java

src/main/java/teetime/stage/string/WordCounter.java

...main/java/teetime/stage/taskfarm/ITaskFarmDuplicable.java

src/main/java/teetime/stage/taskfarm/TaskFarmStage.java

...t/java/teetime/framework/CompositeCounterIncrementer.java

src/test/java/teetime/framework/CompositeProducerStage.java

src/test/java/teetime/framework/CompositeStageTest.java

...eetime/stage/taskfarm/TaskFarmStageTestConfiguration.java