title: How to target multiple frameworks in VS2017 final?
body: <p>For ASP.NET Core I could target multiple frameworks (for example <code>netcoreapp1.1</code> and <code>dnx451</code>) in one Project.json:</p>
  
  <pre><code>"frameworks": {
     "netcoreapp1.1": {
       "dependencies": {
         "Microsoft.NETCore.App": {
           "version": "1.1.0",
           "type": "platform"
         }
       },
       "imports": [
         "dotnet5.6",
         "portable-net45+win8"
       ]
     },
     "dnx451": {}
   },
  </code></pre>
  
  <p>In the final Version of Visual Studio 2017 I can only target either <code>netcoreapp1.1</code> or <code>dnx451</code>, but I see no way to target both.</p>
  
  <p>I tried editing the csproj-file directly to add a 2nd Framework by Setting either <code>&lt;TargetFramework&gt;netcoreapp1.1;dnx451&lt;/TargetFramework&gt;</code> or even  <code>&lt;TargetFrameworks&gt;netcoreapp1.1;dnx451&lt;/TargetFrameworks&gt;</code> but get Errors in Visual Studio due to unsupported frameworks.</p>
  
  <p>So how Do I target both <code>netcoreapp1.1</code> and <code>dnx451</code> in one project in the final version of Visual Studio 2017?</p>