Created a simple GUI installation script...

* Users can navigate to 'path\to\PhpRbac\install.php' in their web browser, enter database credentials and click submit. The installer will then create a proper 'path\to\PhpRbac\database\database.config' file, create the requested database and tables if they do not exist, and then populate the database tables with the required initial data

* Includes minimal error checking
    * Makes sure all fields are populated
    * Makes sure the passwords match