library/roles/nginx/templates/nginx-proxy-params.conf.j2: Add a new parameter to work better when keepalive is active.

nginx/templates/nginx-proxy-params.conf.j2

@@ -1,6 +1,7 @@
 # Proxy stuff
 # include /etc/nginx/snippets/nginx-proxy-params.conf;
 proxy_http_version 1.1;
+proxy_set_header Connection "";
 {% if haproxy_ips is defined %}
 proxy_set_header Host $http_host;
 proxy_set_header X-Real-IP $remote_addr;