Updates to Flask installation

Some additional details:

• virtualenv is not installed by default do this with
  
  

  pip3 install virtualenv

  https://gist.github.com/frfahim/73c0fad6350332cef7a653bcd762f08d
• If the wrong version of mod_wsgi is installed, remove it with
  
  

  sudo apt-get remove --auto-remove libapache2-mod-wsgi

  http://blog.ubiq.co/how-to-uninstall-mod_wsgi-from-ubuntu/
• Install the correct version of mod_wsgi with
  
  

  sudo apt-get install apache2-dev
  pip install mod_wsgi
  sudo /mod_wsgi-express install-module

  Copy the LoadModule line from the output into file /etc/apache2/mods-available/wsgi.load
  https://pypi.org/project/mod_wsgi/
• Enable mod_wsgi
  
  

  sudo a2enmod wsgi
  sudo service apache2 restart

... and one gotcha

The name of the wsgi script file must be in lowercase (!)