Remove Connection: close header for 501 error handling rest

Ralf doesn't know why the "Connection: close" header was added. Was
there since the original code to support OPTIONS verb was added.
He agrees it can be removed.

Enable test for that code path.

Commit the code not just the test....

Author: rouilj

roundup/cgi/wsgi_handler.py

@@ -98,8 +98,8 @@ def __call__(self, environ, start_response):
             else:
                 code = 501
                 message, explain = BaseHTTPRequestHandler.responses[code]
-                request.start_response([('Content-Type', 'text/html'),
-                                        ('Connection', 'close')], code)
+                request.start_response([('Content-Type', 'text/html')],
+                                       code)
                 request.wfile.write(s2b(DEFAULT_ERROR_MESSAGE % locals()))
                 return []