I have the RTM of Visual Studio installed, but the WebApi NuGet RTM build isn’t available yet. WebApi depends on Newtonsoft.Json and so does Twitterizer, but there is a version conflict.
Unfortunately the solution to this error: “Updating ‘Newtonsoft.Json 4.5.8’ to ‘Newtonsoft.Json 4.5.5’ failed. Unable to find a version of ‘Microsoft.AspNet.WebApi.Client’ that is compatible with ‘Newtonsoft.Json 4.5.5’.” is to uninstall WebApi from the project and then install Twitterizer.
For now, until WebApi RTMs, you can’t have both twitterizer and WebApi installed in the same project. You can easily just create another WebApi project that doesn’t need twitterizer.
Sorry for the hassle. Should be fixed with WebApi RTMs. Which should be soon.