title: Package tried to add reference to System.Runtime which was not found in the GAC
body: <p>ASP.NET 4.5.1 or 4.5.2</p>
  
  <p>Updating Nuget package MicrosoftAspNet.Identity.EntityFramework from version 2.2.1 to version 3.0.0-rc1-final</p>
  
  <p>I get the following error:</p>
  
  <p>Failed to add reference. The package 'Microsoft.AspNet.Identity.EntityFramework' tried to add a framework reference to 'System.Runtime' which was not found in the GAC. This is possibly a bug in the package. Please contact the package 
  owners for assistance.</p>