Easier platform management and added support for translation and spotify...

... on Linux

To open a link in a browser, just use Command.browser(link), and it will work on Mac, Linux and Windows (and eventually on the others).

To use interprocess communication (like dbus or osascript), use Command.bus(script). The script should be like : {osx:"script on osx", linux:"script on linux"}.

See the examples in spotify.rb for more info