title: How to use "old" dependencies with ASP.NET 5
body: <p>I've created a new project using a clean install of VS 2015 Enterprise RC1, and I'm trying to add a Nuget package for <a href="https://www.nuget.org/packages/Mandrill/" rel="noreferrer">Mandrill</a> which is built against .NET 4.</p>
  
  <p>When I build the project i get an error from DNX Core 5.0 that the namespace cannot be found:</p>
  
  <pre><code>All packages are already installed and there is nothing to restore.
  NuGet package restore finished.
  1&gt;------ Build started: Project: WebApplication3, Configuration: Debug Any CPU ------
  1&gt;C:\Projects\WebApplication3\src\WebApplication3\MessageServices.cs(5,7,5,15): DNX Core 5.0 error CS0246: The type or namespace name 'Mandrill' could not be found (are you missing a using directive or an assembly reference?)
  1&gt;
  1&gt;  Build failed.
  1&gt;           0 Warning(s).
  1&gt;           1 Error(s).
  1&gt;
  1&gt;  Time elapsed 00:00:00.1404086
  1&gt;
  ========== Build: 0 succeeded or up-to-date, 1 failed, 0 skipped ==========
  </code></pre>
  
  <p>Rather than add as a global dependency, I've tried to add it just to the dnx451 framework within <code>project.json</code>, with the same result.</p>
  
  <pre><code>"frameworks": {
      "dnx451": {
          "dependencies": {
              "Mandrill": "1.3.1"
          }
      },
      "dnxcore50": { }
  },
  </code></pre>
  
  <p>Is it even possible to use .NET 4 packages with ASP.NET 5? If so, what's required?</p>