Added default_server directive to gitlab site conf

Without the default_server site nginx never gets to call the application, it keeps displaying the "Welcome to nginx" page

Author: rafaelrosafu

nginx/gitlab

@@ -7,7 +7,7 @@ upstream gitlab {
 }
 
 server {
-  listen YOUR_SERVER_IP:80;         # e.g., listen 192.168.1.1:80;
+  listen YOUR_SERVER_IP:80 default_server;         # e.g., listen 192.168.1.1:80;
   server_name YOUR_SERVER_FQDN;     # e.g., server_name source.example.com;
   root /home/gitlab/gitlab/public;