api/status: include default units and apiEnabled

Responses look like:
```bash
curl localhost:1337/api/v1/status.json | json
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    87  100    87    0     0  48739      0 --:--:-- --:--:-- --:--:-- 87000
{
  "status": "ok",
  "apiEnabled": true,
  "units": "mg/dl",
  "version": "0.3.0",
  "name": "Nightscout"
}
```
tweak comment
Merge branch 'rebase/settings' of github.com:nightscout/cgm-remote-monitor into rebase/settings