Fix whitespace and then some

Operations performed:

- Reformat code (IntelliJ function)
- Optimized the imports (IntelliJ function)
- Converted CRLF line endings to LF line endings (only in the grails-app and test)
- Added a .gitattributes file to ensure only LF line endings are stored in Git
- Removed empty test files

Let's make sure this is never needed again!