Issue2005 build dsn differently on Windows/*unix

Issue #2005

The dsn should be constructed differently between these 2 platforms.

Windows uses a comma before a port number, *nix uses a colon. Otherwise, users receive an 'Unknown host machine name' error.

References:

http://php.net/manual/de/ref.pdo-dblib.connection.php
http://forums.laravel.io/viewtopic.php?id=11033

My last PR was closed because it inadvertently included a .gitignore file

I am re-submitting a proper PR