create drush status command

[amirkdv]

Currently we run "drush si" only_if DRUSH_STATUS_CMD:

drush status --fields=db-status
  | grep Connected
  | wc -l
  | xargs test 0 -eq

This needs to be refind. Currently, if settings.php is missing, this will obliterate the database. Also look at this in the dev-notes.

[amirkdv]

Along the same line, it would be more robust to use a drush command instead of test -f /path/to/index.php to check for an existing Drupal site.