last commit breaks up all pybullet demos

[egordv]

Hello Junhyeokahn and thank you for a great repo!
It seems that ad8d19e breaks all the demos.
At this commit Draco3 demo is falling through the floor just after the simulation starts.
Both Atlas demos (dart/pybullet) fails to run with Error reading parameter [n_steps] at file: [PnC/pnc/whole_body_controllers/managers/dcm_trajectory_manager.cpp]
At 2ddaa6e the situation is better - Atlas demo works as expected, and Draco3 demo is at least able to walk but very unstable leading to a fall after several steps