I was confused when landed at the Microsoft SQL Server Data Tools page http://msdn.microsoft.com/en-US/data/tools.aspx. It was taking quite a while for me to figure out SSDT comes with Visual Studio and it is not a standalone tool to use without Visual Studio. Somehow you are about to update the SSDT separately. To install SSDT update read http://blogs.msdn.com/b/ssdt/archive/2014/07/15/sql-server-data-tools-july-update.aspx?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+ssdtblog+%28SQL+Server+Developer+Tools+Team+Blog%29.
I am not sure how long this SSDT strategy will last, at the meantime this is the approach for SSDT.