error MSB8031: Building an MFC project for a non-Unicode character set is deprecated. You must change the project property to Unicode or download an additional library.

It dues to the MFC support for multi-byte character set (MBCS) is deprecated in Visual Studio 2013, and it can be solved by installing the Multibyte MFC Library for Visual Studio 2013 in
http://www.microsoft.com/en-us/download/confirmation.aspx?id=40770

more details on Visual C++ Team Blog