Add support for MSSQL jTDS driver

Pull request to resolve issue freekh/play-slick#76: "Possible incompatibility with MS SQL Server JTDS".

The solution is just to add the driver name to the `driverByName` method. SQL syntax is already supported, since it's MS SQL server.

See also corresponding thread on Stack Overflow: http://stackoverflow.com/questions/18025256/connecting-to-mssql-with-play-and-slick