Fix ControlBoardWrapper behaviour if the device name does not contains //

Without this, ControlBoardWrapper will raise a std::replace exception when processing device names that does not contain "//". 
This was silently breaking the gazebo controlboard and I am afraid is breaking all the properly configured controlboard wrappers, even the one on the real robot. 

@barbalberto aside from this bug, this replace call is a bit suboptimal. 
Introducing an undocumented behaviour in loading configuration instead of fixing a malformed configuration file is harmful.