yle-dl: download stuff from areena.yle.fi

Good day! [yle-dl](http://aajanki.github.com/yle-dl/index-en.html) is a youtube-dl-like tool for downloading media files from Finnish national broadcast company's streaming service [YLE Areena](http://areena.yle.fi/). 

Since the previous pull requests (#9418 and #4149):

* yle-dl no longer requires a modified version of RTMPDump (since RTMPDump 2.4)
* yle-dl is less niche, as lots more people are using it (though usually via less user-friendly gui versions)
* homebrew-alt (which had the old rtmpdump-yle) [has been retired](http://librelist.com/browser//homebrew/2012/12/15/retiring-homebrew-alt/)
* also yle-dl a dependency for my [muumi-dl](/sampumon/muumi-dl) auto-downloader, and would like to have the dependency work automatically!