Add a wsgi.py file, which is useful for using gunicorn

Now that this file is present in the respository, you can
use gunicorn for CATMAID's django backend with:

  cd ~/catmaid/django/projects
  gunicorn -b 127.0.0.1:8020 mysite.wsgi:application
Change requests from POST to GET for methods where the POST arguments are never read.
This was needed to make uWSGI work without buffering POST data.
Add documentation on how to let Nginx serve Django's static files
Merge pull request #479 from perlman/httpfix

Change from POST to GET for several methods.
Installation notes for nginx with uwsgi.