MLS Validation Service Version (#1156)

For node-partners we require publicly versioned docker images.

I picked 0.1.0 since `mls-validation-service` has been around for a bit and it does not feel like `0.0.1`

Also added some convenience methods to print `--version`

The format is as follows:
```
$ docker run --rm af4389d1bb47 --version
Version: 0.1.0-a7bd4b5
```

Author: mkysel