title: How to see request user-agent in Heroku logs
body: <p>I have a Heroku app where I want to see the user-agent clients are using for their requests.  When I do:</p>
  
  <pre><code>hk logs --app myapp
  </code></pre>
  
  <p>I see lots of interesting info, but not the HTTP request headers or the User-Agent.  Is there a way to get these, or is there a way to tell Heroku to log these for future requests?</p>