Revert "Fix position direct and improve compliance with yarp controlboar...

Reverts robotology/gazebo-yarp-plugins#138
I did an error. Just tried the right version and I have WARNINGS and ERRORS and the robot does not move at all:

Error while trying to command a streaming position direct message on all joints
[WARN] gazebo_yarp_controlboard: you tried to call setPosition
[WARN] for a joint that is not in POSITION_DIRECT control mode.
[WARN] gazebo_yarp_controlboard: you tried to call setPosition
[WARN] for a joint that is not in POSITION_DIRECT control mode.
[WARN] gazebo_yarp_controlboard: you tried to call setPosition
[WARN] for a joint that is not in POSITION_DIRECT control mode.
[WARN] gazebo_yarp_controlboard: you tried to call setPosition
[WARN] for a joint that is not in POSITION_DIRECT control mode.
[WARN] gazebo_yarp_controlboard: you tried to call setPosition
[WARN] for a joint that is not in POSITION_DIRECT control mode.
[WARN] gazebo_yarp_controlboard: you tried to call setPosition
[WARN] for a joint that is not in POSITION_DIRECT control mode.
[WARN] gazebo_yarp_controlboard: you tried to call setPosition
[WARN] for a joint that is not in POSITION_DIRECT control mode.