Fix System.Web.Mvc reference

Set System.Web.Mvc reference CopyLocal to true in OAuth2ProtectedWebApi.csproj.
Since a recent security update, the project will fail at runtime without this.
References: 
http://blogs.msdn.com/b/webdev/archive/2014/10/16/microsoft-asp-net-mvc-security-update-broke-my-build.aspx
http://stackoverflow.com/questions/26406804/after-windows-update-the-type-or-namespace-name-html-does-not-exist-in-the-na