Issue title: Outdated cask: boxer
 Issue body: Outdated cask: [`boxer`](https://github.com/caskroom/homebrew-cask/blob/master/Casks/boxer.rb).

Info:
- version: `1.3.2-20120713`.
- appcast url: http://boxerapp.com/appcast.

 Comments: 
 Comment 0: Closing in favour of #19045.
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