Add .NET Framework 4.6 and Visual Studio 2015 to platforms.json
Add .NET Framework 4.6 and Visual Studio 2015 to platforms.json

punker76/dotnet,BruceForstall/dotnet,BruceForstall/dotnet,punker76/dotnet,velyo/dotnet,richlander/dotnet,Microsoft/dotnet,velyo/dotnet,690486439/dotnet,Microsoft/dotnet,richlander/dotnet