Upgraded to VS2013

Signed-off-by: Rick Minerich <richard.minerich@gmail.com>
Updated to FSharp.Core 4.3.1.0
Now fully upgraded to .NET 4.51

Signed-off-by: Rick Minerich <richard.minerich@gmail.com>
removed key annotation

Signed-off-by: Rick Minerich <richard.minerich@gmail.com>