Update copyright year to 2019.

LICENSE

@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2014-2018 The Bootlint Authors
+Copyright (c) 2014-2019 The Bootlint Authors
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -244,4 +244,4 @@ See the [GitHub Releases page](https://github.com/twbs/bootlint/releases) for de
 
 ## License
 
-Copyright (c) 2014-2018 The Bootlint Authors. Licensed under the MIT License.
+Copyright (c) 2014-2019 The Bootlint Authors. Licensed under the MIT License.

src/bootlint.js

@@ -1,7 +1,7 @@
 /*
  * Bootlint - an HTML linter for Bootstrap projects
  * https://github.com/twbs/bootlint
- * Copyright (c) 2014-2018 The Bootlint Authors
+ * Copyright (c) 2014-2019 The Bootlint Authors
  * Licensed under the MIT License.
  */