fix nginx conf (#896)

* fix nginx conf

server-ce/nginx/sharelatex.conf

@@ -9,6 +9,7 @@ server {
 		proxy_http_version 1.1;
 		proxy_set_header Upgrade $http_upgrade;
 		proxy_set_header Connection "upgrade";
+		proxy_set_header Host $host;
 		proxy_set_header X-Forwarded-Host $host;
 		proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
 		proxy_read_timeout 10m;
@@ -20,6 +21,7 @@ server {
 		proxy_http_version 1.1;
 		proxy_set_header Upgrade $http_upgrade;
 		proxy_set_header Connection "upgrade";
+		proxy_set_header Host $host;
 		proxy_set_header X-Forwarded-Host $host;
 		proxy_set_header X-Forwarded-Proto $scheme;
 		proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;