F hand driver prefix

Fixes #41 
no I meant: `rh EtherCAT Dual CAN Palm` 

in the code:

```
string prefix = device_id_.empty() ? device_id_ : (device_id_ );
d.name = prefix + "EtherCAT Dual CAN Palm";
prefix = device_id_.empty() ? device_id_ : (device_id_  + "/");
```

Anyway I'm OK with the current solution.