Cropping: remove usage of Hop-by-hop 'Connection' header
Cropping: remove usage of Hop-by-hop 'Connection' header

According to PEP 333 (WSGI), applications are not allowed to use such headers:

  Applications and middleware are forbidden from using HTTP/1.1 "hop-by-hop"
  features or headers, any equivalent features in HTTP/1.0, or any headers that
  would affect the persistence of the client's connection to the web server.

  (http://www.python.org/dev/peps/pep-0333/)

If in use, some WSGI servers raise errors (i.e. django-devserver).

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