Allow application to set the read deadline when reading the response body

[garyburd]

If an application can specify the read deadline when reading the response body, then the application can easily detect dropped connections for Twitter streaming endpoints and similar services.

The following snippet of code shows how an application can use the feature. The Twitter streaming endpoints write a blank keep alive line very 30 seconds.

scanner := bufio.NewScanner(body)
body.SetReadDeadline(time.Now().Add(40 * time.Second))
for scanner.Scan() {
    p := scanner.Bytes()
    if len(p) > 0 {
        processTweet(p)
    }
   body.SetReadDeadline(time.Now().Add(40 * time.Second))
}