[permissions] Rename PermissionStatus.status to PermissionStatus.state (#31)

`PermissionStatus` has an attribute called `status` that is of type `PermissionState`. This seems to mildly confuse one with the other. It would be more correct to rename the attribute to `state` to correctly reflect its type. The geolocation javascript example should then read as follows:

``` javascript
navigator.permissions.query({name:'geolocation'}).then(function(status) {
    if (status.state == 'granted') {
      showLocalNewsWithGeolocation();
    } else if (status.state == 'prompt') {
      showButtonToEnableLocalNews();
    }
    // Don't do anything if the permission was denied.
  });
```

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/permissions/issues/31