text: Title: Docs recipe: stream media with range request
  Body: Hello, 
  
  i'm tryning to stream mp4 video, with range request support.but i cannot manage to make it work with resp.stream.
  
  This code work :
  
  ```
  def on_get(self, req, resp):        
          media = 'test.mp4'
          resp.set_header('Content-Type', 'video/mp4')
          resp.accept_ranges = 'bytes'            
          stream = open(media,'rb')
          size = os.path.getsize(media)            
          if req.range :        
                  end = req.range[1]
                  if end < 0 :
                      end = size + end
                  stream.seek(req.range[0])                
                  resp.content_range = (req.range[0],end,size)
                  size = end - req.range[0] + 1
                  resp.status = falcon.HTTP_206
           resp.content_length = size
           resp.body = stream.read(size)
  
  ```         
  but this will load all file in memory, which is not an option.
  
  if i change the 2 last line with
  `resp.set_stream(stream,size)`,
  
  i've got an error 
  
  ```
  SIGPIPE: writing to a closed pipe/socket/fd (probably the client disconnected) on request /api/stream/557 (ip 10.0.0.136) !!!
  uwsgi_response_sendfile_do(): Broken pipe [core/writer.c line 645] during GET /api/stream/557 (10.0.0.136)
  IOError: write error
  ```
  
  i'm using uwsgi with nginx as reverse proxy. Not sure it's related to falcon, but i don't have any clue where to look at.
  
  Any idea?
  
  Thanks
  
  Johan
  
  Ps : i know it's not optimal to use falcon for this, but i cannot expose real video path to client (in real in come from a db). and performance are not really a problem in my case.
  
  
  Edit :
  Here's the chrome requests when it don't work.
  | Name | Url | Method | Status | Protocol |type | initiator | size | time
  |--|--|--|--|--|--|--|--|--|
  557      | http://10.1.12.2/api/stream/557 | GET       | 206            | http/1.1 | media | Other |   32.6 kB | 5.24 s   | 50883753
  557      | http://10.1.12.2/api/stream/557 | GET       | 206            | http/1.1 | media | Other |   28.1 kB | 365 ms | 27817
  557      | http://10.1.12.2/api/stream/557 | GET       | (canceled) |              | media | Other |   0 B        | 1 ms
  