Update dbInstall.php: Fix the require_once to match other scripts
Update dbInstall.php: Fix the require_once to match other scripts

- Update dbInstall.php:
 * Without the __DIR__ context, it will fail when the script is
   executed from directory other than testswarm root
   (e.g. `./scripts$ php dbInstall.php`
   or `jquery$ php testswarm/scripts/dbInstall.php`)

- closes #180

newzly/testswarm,newzly/testswarm,newzly/testswarm,newzly/testswarm