Correct copyright dates and enforce that starting year is 2012

Closes gh-7923

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/mvc/JolokiaMvcEndpoint.java

 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2012-2017 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.

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/DiskSpaceHealthIndicator.java

 /*
- * Copyright 2014-2016 the original author or authors.
+ * Copyright 2012-2017 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.

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/reader/MetricRegistryMetricReader.java

 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2012-2017 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.

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/rich/MultiMetricRichGaugeReader.java

 /*
- * Copyright 2014-2014 the original author or authors.
+ * Copyright 2012-2017 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.

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/mvc/JolokiaMvcEndpointContextPathTests.java

 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2012-2017 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.

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/mvc/JolokiaMvcEndpointIntegrationTests.java

 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2012-2017 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.

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mustache/MustacheProperties.java

 /*
- * Copyright 2013-2015 the original author or authors.
+ * Copyright 2012-2017 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.

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/Http401AuthenticationEntryPoint.java

 /*
- * Copyright 2013-2015 the original author or authors.
+ * Copyright 2012-2017 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.

spring-boot-cli/src/main/java/org/springframework/boot/cli/command/install/InstallCommand.java

 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2012-2017 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.

spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/SmartImportCustomizer.java

 /*
- * Copyright 2013-2014 the original author or authors.
+ * Copyright 2012-2017 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.

spring-boot-parent/src/checkstyle/checkstyle-header.txt

 ^\Q/*\E$
-^\Q * Copyright \E20\d\d\-20\d\d\Q the original author or authors.\E$
+^\Q * Copyright \E2012-20\d\d\Q the original author or authors.\E$
 ^\Q *\E$
 ^\Q * Licensed under the Apache License, Version 2.0 (the "License");\E$
 ^\Q * you may not use this file except in compliance with the License.\E$

spring-boot-test/src/main/java/org/springframework/boot/test/IntegrationTestPropertiesListener.java

 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2012-2017 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.