Making Drupal Framework Install not fail when a mail system doesn't exist

By setting send mail to true for the one command, we are circumventing drupal install from failing because there is no way to set the mail system before install however, drupal does send an email to the site administrator in order to let them know that a new version is ready of drupal.

Also switching drush.php to drush so that we can use the robustness of the already existing bashscript to run drush.