Updated gitignore

- Added IntelliJ IDEA project file types to .gitignore
- Added *.*~ to .gitignore
Added Linux, BSD to OSDetector
Added "shutdown when render completes"

- Support for Windows and Unix-like (Linux, Mac OSX, BSD), shutdown countdown
- Instructions on how to set "sudo shutdown" to not require a password so the
  feature works on Unix-like systems
- Added "Shutdown when render completes" to changelog
Cleaned up pull request

Fixed the following problems in previous commit (pull request):

- fixed incorrect Copyright date
- removed redundant inner class
- fixed formatting (indentation, brace style etc.)
- log error when shutdown command fails
- converted comments to JavaDoc
- don't throw unchecked exception
- fixed UI layout

fixes #24 (github)