Avoid response buffering for ISeq response body

[kumarshantanu]

This PR makes StreamableResponseBody implementation for ISeq avoid response buffering, which is useful when the ISeq elements are delayed at source. This also allows for a smooth Server-sent Events flow.

Consider the example usage below:

(defn make-seq []
  (Thread/sleep #_10 1000)
  (str "data: " (System/currentTimeMillis) "\n\n"))

(defn handler [request]
  {:status 200
   :headers {"Content-Type" "text/event-stream"}
   :body (repeatedly make-seq)})

[weavejester]

Thanks for the PR. Can you ensure the commit messages follow the seven rules of a great git commit message as mentioned in the contributing guidelines.

Secondly, can you think of a way of testing the changes you've made?

[kumarshantanu]

@weavejester Thanks for the feedback - I have made the changes (edited the commit message, and reverted a commit that broke a test).

[weavejester]

Thanks! Can you remove the commit you reverted and its reversion, so there's just one commit left. Can you also add a test for the change you made.

[kumarshantanu]

Created PR #528 with removed unwanted commits, and a test for flushing of body.

[weavejester]

For future reference, you don't need to create a new PR to do this. You can just force-push your changes and the PR will be updated. This is preferred, as it keeps the comments in one place.

[kumarshantanu]

Noted. Force push after a git reset (to get rid of the unwanted commits) automatically closed the PR, so it was accidental. I should have made the new commits before the force push.