Make language choice available when installing with drush

Since there are translated sql files, they have to be used for installation, but drush civicrm-install command doesn't provide any ability to do that.
This patch adds two options : --lang and --langtarfile which alows the initialisation with a translated database.
Note : If lang is provided, langtarfile is required.

The command line should look like this one :
"""
drush civicrm-install --dbuser=$

{CIVICRM_BDD_USER}

--dbpass=$

{CIVICRM_BDD_PWD}

--dbname=$

{CIVICRM_BDD}

--tarfile=$

{TMP_DIR}civicrm-4.0.4-drupal.tar --destination=sites/all/modules --dbhost=localhost --lang=fr_FR --langtarfile=${TMP_DIR}

civicrm-4.0.4-l10n.tar
"""