Update --download JSON output to be sane

This PR cleans up the brain spew that was the original output of the `--download` parameter and turns it into something a bit more useful. Example:

```
{
    currentVersion: "1.0.0.0",
    futureVersion: "1.0.0.1",
    releasesToApply: [
        {
            version: "1.0.0.1",
            releaseNotes: "This does a thing"
        }
    ]
}
```