OPEN - issue BATCH-368: StepExecution attributes can overflow and cause spurious OptimisticLockingException

http://jira.springframework.org/browse/BATCH-368

Split the save of a StepExecution into two parts at the JobRepository level, that way we can see if the failure was in saving context or just the step execution.
Lots of exception handling and tests in step implementations.

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/exception/CommitFailedException.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2006-2007 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.batch.item.exception;
+
+/**
+ * @author Dave Syer
+ *
+ */
+public class CommitFailedException extends StreamException {
+	/**
+	 * @param message
+	 */
+	public CommitFailedException(String message) {
+		super(message);
+	}
+
+	/**
+	 * @param msg
+	 * @param nested
+	 */
+	public CommitFailedException(String msg, Throwable nested) {
+		super(msg, nested);
+	}
+
+	/**
+	 * @param msg
+	 * @param nested
+	 */
+	public CommitFailedException(Throwable nested) {
+		super(nested);
+	}	
+
+}