OperationalError: (OperationalError) (2003, "Can't connect to MySQL server on '192.168.129.139' (111)") None None
Looks like mysql is configured to listen only on localhost.
You can test this by running
telnet 192.168.129.139 3306 from your client machine.
Most probable reason - mysqld is configured to do so.
Please try to follow Configuration step described here:
/etc/mysql/my.cnf file to configure MySQL to listen for connections from network hosts, change the bind-address directive to the server's IP address. For example Replace 192.168.0.5 with the appropriate address. If there are no such entry - uncomment it or create new line.
bind-address = 192.168.0.5
Then restart mysqld
sudo service mysql restart
Then test with telnet or by running your application once again. Also netstat would have second entry for mysqld.