Update to 2.2.8
    
    - New upstream release 2.2.8
      - A bugfix release with some small improvements and more polished existing
        features
      - Fixes a few serious but rarely occuring bugs
      - Options defined in the language definition files are now translated
      - Various default settings have been improved, most notably the command to
        launch Firefox for preview
      - The looks on newer GTK versions have been restored
      - CSS can now be compressed and decompressed
      - The installers for Windows and OSX have improvements, and there have been
        some OSX and Windows specific fixes
      - Character encoding detection has been improved.
      - Auto-completion for HTML attributes has been improved
    - Don't replace new upstream AppData screenshot
    - Bump python requirement to 2.7, needed for CSS decompressor