OPEN - issue BATCH-324: Step as factory for StepExecutor

http://jira.springframework.org/browse/BATCH-324

First pass - added factory method, resolved conflicts and cycles, got tests working.

spring-batch-samples/src/main/java/org/springframework/batch/sample/tasklet/ExceptionRestartableTasklet.java

@@ -41,7 +41,7 @@ public class ExceptionRestartableTasklet extends RestartableItemOrientedTasklet
 		
 		counter++;
 		if (counter == throwExceptionOnRecordNumber) {
-			throw new BatchCriticalException();
+			throw new BatchCriticalException("Planned failure on count="+counter);
 		}
 		
 		return super.execute();