Add check header rule and fixHeaders task

Add "new line" in the header end

* Optimization for the `fixHeaders.gradle`
* Apply the `fixHeaders` for the affected classes

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/event/ReceiptEvent.java

@@ -1,11 +1,11 @@
 /*
- * Copyright 2015 the original author or authors
+ * Copyright 2015-2016 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
+ *      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,