Merging changes for ticket 620 into production

includes/unl_bootstrap.inc

includes/update.inc

sites/all/modules/drush/README.txt

sites/all/modules/drush/commands/core/clear.cache.inc

sites/all/modules/drush/commands/core/core.drush.inc

sites/all/modules/drush/commands/core/drupal/batch_6.inc

sites/all/modules/drush/commands/core/drupal/batch_7.inc

.../all/modules/drush/commands/core/drupal/environment_5.inc

.../all/modules/drush/commands/core/drupal/environment_6.inc

.../all/modules/drush/commands/core/drupal/environment_7.inc

...all/modules/drush/commands/core/drupal/site_install_6.inc

...all/modules/drush/commands/core/drupal/site_install_7.inc

sites/all/modules/drush/commands/core/drupal/update_5.inc

sites/all/modules/drush/commands/core/drupal/update_6.inc

sites/all/modules/drush/commands/core/drupal/update_7.inc

sites/all/modules/drush/commands/core/field.drush.inc

sites/all/modules/drush/commands/core/rsync.core.inc

sites/all/modules/drush/commands/core/scratch.php

sites/all/modules/drush/commands/core/site_install.drush.inc

sites/all/modules/drush/commands/core/sitealias.drush.inc