title: Remove unnecessary HTTP headers in my rails answers
body: <p>I am currently developing an API where size matters: I want the answer to contain as few bytes as possible. I optimized my JSON answer, but rails still responds with many strange headers</p>
  
  <pre><code>HTTP/1.1 200 OK
  Server: nginx/0.7.67                            # Not from Rails, so ok.
  Date: Wed, 25 Apr 2012 20:17:21 GMT             # Date does not matter. We use ETag Can I remove this?
  ETag: "678ff0c6074b9456832a710a3cab8e22"        # Needed.
  Content-Type: application/json; charset=utf-8   # Also needed.
  Transfer-Encoding: chunked                      # The alternative would be Content-Length, so ok.
  Connection: keep-alive                          # Good, less TCP overhead.
  Status: 200 OK                                  # Redundant! How can I remove this?
  X-UA-Compatible: IE=Edge,chrome=1               # Completely unneded.
  Cache-Control: no-cache                         # Not needed.
  X-Request-Id: c468ce87bb6969541c74f6ea761bce27  # Not a real header at all.
  X-Runtime: 0.001376                             # Same goes for this
  X-Rack-Cache: invalidate, pass                  # And this.
  </code></pre>
  
  <p>So there are lots of unnecessary HTTP headers. I could filter them in my server (nginx), but is there a way stop this directly in rails?</p>