title: System.Web.Http missing after .net 4.5 upgrade
body: <p>I've just upgraded my solution to .net 4.5 using <a href="https://visualstudiogallery.msdn.microsoft.com/47bded90-80d8-42af-bc35-4736fdd8cd13">Target Framework Migrator</a>, and then the package manager console command: </p>
  
  <p><code>Update-Package -Reinstall -IgnoreDependencies</code></p>
  
  <p>In one of my projects I am using:</p>
  
  <pre><code>using System.Web.Http.Controllers;
  using System.Web.Http.Filters;
  </code></pre>
  
  <p>The code uses <code>HttpActionContext</code> and <code>ReflectedHttpActionDescriptor</code>. I notice that <code>System.Web.Http</code> has been removed from my references, and is no longer available in the Add New Reference window. What's going on?</p>