title: Specify the application base path in ConfigurationBuilder in beta8
body: <p>I used to specify the application base path for the <code>ConfigurationBuilder</code> like this: </p>
  
  <pre><code>public Startup(IApplicationEnvironment appEnv)
  {
      var configurationBuilder = new ConfigurationBuilder(appEnv.ApplicationBasePath)
          .AddJsonFile("config.json")
          .AddEnvironmentVariables();
  
      Configuration = configurationBuilder.Build();
  }
  </code></pre>
  
  <p>However, as of beta8, the constructor of <code>ConfigurationBuilder</code> does not take an application base path argument anymore and it throws an exception now. </p>
  
  <p>How can I specify the base path?</p>