Fix front health checking

- Specified seperated /health path in order to allow for healthcheck even if webmail and admin are not seletectd. This also allows healthchecking fom external services like DNS load balancers;
- Make curl not to fail on TLS because localhost is not included in the certificates.

core/nginx/conf/nginx.conf

@@ -146,6 +146,10 @@ http {
         proxy_pass_request_body off;
         proxy_set_header Content-Length "";
       }
+
+      location /health {
+        return 204;
+      }
     }
 
     # Forwarding authentication server