title: How to access session from DS.RESTAdapter?
body: <p>I am building an Ember-CLI application. I use ember-cli-simple-auth-devise. I have successfully authenticated from back-end and got API token. In order to send the token in each request header I am trying the following code as described here <a href="http://emberjs.com/api/data/classes/DS.RESTAdapter.html#toc_headers-customization" rel="nofollow">http://emberjs.com/api/data/classes/DS.RESTAdapter.html#toc_headers-customization</a></p>
  
  <pre><code>import DS from "ember-data";
  
  export default DS.RESTAdapter.extend({
    host: "http://localhost:3000",
    namespace: "api/v1",
    headers: function() {
      return {"X-Access-Token": this.get("session.user_token")};
    }.property("session.user_token")
  });
  </code></pre>
  
  <p>But this does not work. I inspected</p>
  
  <pre><code>this.get("session.user_token")
  </code></pre>
  
  <p>Which results undefined. So the session is not accessible ins DS.RESTAdapter. How to make the session helper available for DS.RESTAdapter? </p>