The wake and shutdown command may reveal secrets used
### Backstory
It has come to my attention that some wake and shutdown commands (such as `net rpc ...`) may need username and passwords in the command itself. SSH, for example allows for the sensible solution to use key authentication - but not all commands may allow such a workaround. Since the current version of homebridge-wol may log the commands being used, these username and passwords may be visible in the terminal output or a log file. 

### Issue
[This line](https://github.com/AlexGustafsson/homebridge-wol/blob/master/lib/network-device.js#L150) logs the wake command which may contain secrets such as a username and or password.

[This line](https://github.com/AlexGustafsson/homebridge-wol/blob/master/lib/network-device.js#L161) logs the shutdown command which may contain secrets such as a username and or password.

### Environment
* homebridge-wol version: 3.2.2

### Notes
A possible solution is to extract the first word and log only that, which may result in logs such as:
> Attempting to wake up "My Windows PC" (192.168.1.151) using "net"

instead of

> Attempting to wake up "My Windows PC" (192.168.1.151) using "net rpc shutdown --ipaddress 192.168.1.151 --user alex%1234"

Another solution would be to omit all details about the command used.

This issue is great for anyone that may have just started out in open source and or javascript.