Fix drupal 7 settings template (platform->publish_path removed)

[valkum]

$this->platform->publish_path seems to be removed from the platform context and thus in a sites settings.php the platform settings code results in:

  if (is_readable('/sites/all/platform.settings.php')) {
    include_once('/sites/all/platform.settings.php');```

platform->root seems to yield the correct path to the platform

[helmo]

Thanks.