added rpc command to save files with desired root name

Please consider merging, changing names for different scanned objects can be very useful :)
```cpp
if (command.get(0).asString()=="name")
{
    if (command.size()>=2)
    {
        fileName = command.get(1).asString();         
        reply.addVocab(ACK);
    }
    else
    {
        reply.addVocab(NACK);
        reply.addString("No name was provided");
    }
        
    return true;
}
```