Remove the kraken_visualtization dependency.

As per suggestion by @prudhvid at https://github.com/iit-kgp-auv-team/kraken_3.0/issues/38
Add subscriber in the keyboard_control python file.
Complete showing values of the force in the Python GUI
Merge pull request #39 from icyflame/keyboard-control

Keyboard Control: Show values of the force in the Python GUI