Custom Logging level
<!-- If you have an issue with a plugin create an issue on that plugin's GitHub page instead. -->

<!-- Before opening an issue, please review the Troubleshooting Page on the Wiki to ensure that this is a new issue, and alternatively search the closed issues for similar problems. -->

<!-- Link to the the Wiki - https://github.com/nfarina/homebridge/wiki -->

<!-- Provide a general summary in the Title above -->

**Describe Your Problem:**
<!-- A clear and concise description of what problem you are trying to solve. -->

[**Logs:**]()
<!-- Please paste any relevant log output into a gist or using hastebin-->
<!-- If using hastebin or other text sharing website please make the lifespan long-->
<!-- Paste the link between the two () above -->
<!-- Remove any sensitive information, passwords, etc. -->
<!-- Please include the beginning of the log where the homebridge initialization happens -->
<!-- If needing to link multiple log files please do so between the ``` lines below -->

```
Secondary Homebridge Logs here
```

**Homebridge Config:**
<!-- Paste relevant output between the two ``` lines below -->
<!-- Remove any sensitive information, passwords, etc. -->

```json
Show your homebridge config.json here
```

**Screenshots:**
<!-- If applicable, add screenshots to help explain your problem. -->

**Environment:**

* **Node.js Version**: v12.14.0
* **NPM Version**: 6.14.8
* **Homebridge Version**:1.1.7
* **Operating System**: Raspbian /
* **Process Supervisor**: Systemd / hb-service / 

I've installed the Free@home plugin for Homebridge, and this will generate Update messages almost every 10 sec. Needles to say on a raspberry with an SSD card I would like to minimise logging as much as possible unless told otherwise (i.e for debugging).

Would there be anyway to reduce the amount of logging with homebridge? or maybe even to set the level of logging?  

