Add definition 5.4.20 - #155

Signed-off-by: Rogerio Prado de Jesus <rogeriopradoj@gmail.com>
Chmod +x definition 5.4.20 - #155

Signed-off-by: Rogerio Prado de Jesus <rogeriopradoj@gmail.com>
Update STABLE_DEFINITIONS with 5.4.20 - #155

Signed-off-by: Rogerio Prado de Jesus <rogeriopradoj@gmail.com>
Update travis.yml to run 5.4.20 - #155

Fix #155: Need definition for 5.4.20

Signed-off-by: Rogerio Prado de Jesus <rogeriopradoj@gmail.com>