Always try to load servers list from config file

Otherwise, servers list is not loaded if the configuration file also
have an ogServer declared in the deprecated way.

ogcp/og_server.py

@@ -50,7 +50,7 @@ if {'IP', 'PORT', 'API_TOKEN'} <= app.config.keys():
                             app.config['IP'],
                             app.config['PORT'],
                             app.config['API_TOKEN']))
-else:
+if app.config.get('SERVERS'):
     for server in app.config['SERVERS']:
         ogserver = OGServer(server['NAME'],
                             server['IP'],