Only serialize created servers

Any changes to servers that aren't created online need to be manually
added to the configuration file in order for them to take effect after the
restart.

server/core/server.c

@@ -136,6 +136,7 @@ SERVER* server_alloc(const char *name, const char *address, unsigned short port,
     server->monuser[0] = '\0';
     server->monpw[0] = '\0';
     server->is_active = true;
+    server->created_online = false;
     server->charset = SERVER_DEFAULT_CHARSET;
 
     spinlock_acquire(&server_spin);