Keeping original NSURLRequest object HTTPMethod and HTTPBody

Not stripping the original `NSURLRequest` object `HTTPBody` and keeping its `HTTPMethod` gives us the possibility of doing some checks on the server before establishing the websocket. For example, you could have something like this using `ruby`, `sinatra` and `sinatra-websockets`:

```ruby
post '/web-socket-url' do
  if !request.websocket?
    return status 404
  end

  # Without HTTP method post and body data we can't do this in a proper way... Only if we sent
  # this parameter in the query string, what's not good for sensible data
  user_access_token = params[:user_token]

  if !( is_valid_token? user_access_token )
    return status 404
  end

  # Only now we start handling the websocket
  request.websocket do |ws|

    ws.onopen do
      # ...
    end

    ws.onmessage do |message|
      # ...
    end

    ws.onclose do
      # ...
    end
  end
end
```