Python 3 usage

• http://www.phoronix.com/forums/forum/software/distributions/47700-python-3-is-close-to-becoming-the-default-in-fedora-22
• 2015-03-16 "Adapt to the port of Mailman to Python3" http://hyperkitty.readthedocs.org/en/latest/news.html
• http://mailman-bundler.readthedocs.org/en/latest/
  • "Mailman requires at least Python 3.4"
  • !! "Even if Mailman 3 runs on Python 3, the web interfaces and the commands in this procedure run on Python 2.7, so make sure your system Python version is 2.7."