title: Make the ConfigureServices method async in Startup.cs
body: <p>I need to add a couple of await functions in ConfigureServices in Startup.cs and am running into an issue.</p>
  
  <blockquote>
    <p>System.InvalidOperationException
    Unable to find the required services. Please add all the required services by calling 'IServiceCollection.AddMvc()' inside the call to 'IApplicationBuilder.ConfigureServices(...)' or 'IApplicationBuilder.UseMvc(...)' in the application startup code.</p>
  </blockquote>
  
  <p>As seen by the code below, AddMvc &amp; UseMvc are in their correct locations, however, I still get this error.</p>
  
  <pre><code>public async void ConfigureServices(IServiceCollection services)
  {
      ...
      await manager.Initialize();
      var data = await manager.GetData();
      ...
      services.AddMvc();
  }
  
  public void Configure(IApplicationBuilder app, IHostingEnvironment env,ILoggerFactory loggerFactory)
  {
      ...
      app.UseMvc();
      ....
  }
  </code></pre>
  
  <p>Is it possible to make ConfigureServices an async function?</p>