You have to clear the cache like that (because your old configuration is in you cache file) :
php artisan cache:clear
The pdo error comes from the fact Laravel use the pdo driver to connect to mysql
php artisan migrate:install
Hope your problem will get resolved.
Using phpMyAdmin (or whatever you prefer), I just created a database called "forge" and re-ran the php artisan migrate command and it all worked.
php artisan migrate