Response data is always string encoded can't send a binary body  #107

import io
import json
import logging
from PIL import Image, ImageDraw
from fdk import response
def handler(ctx, data: io.BytesIO=None):
    img = Image.new('RGB', (60, 30), color='red')
    d = ImageDraw.Draw(img)
    d.text((10, 10), "hello world", fill=(255, 255, 0))
    # write png image to memory 
    output =  io.BytesIO()
    img.save(output, format="PNG")
    # get the bytes of the image 
    imgbytes = output.getvalue()
    return response.Response(
        ctx, response_data=imgbytes,
        headers={"Content-Type": "image/png"}
    )

(venv) (base) ➜  fdk-python git:(oc/fixBinaryResponses) ✗ curl -v  -X POST http://localhost:8080/invoke/01EC0074S7NG8G00GZJ0000001
*   Trying ::1...
* TCP_NODELAY set
* Connected to localhost (::1) port 8080 (#0)
> POST /invoke/01EC0074S7NG8G00GZJ0000001 HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.54.0
> Accept: */*
>
< HTTP/1.1 200 OK
< Content-Length: 614
< Content-Type: image/png
< Fn-Call-Id: 01EC7NB58GNG8G00GZJ000000D
< Fn-Fdk-Version: fdk-python/dev3
< Date: Thu, 02 Jul 2020 11:42:14 GMT
<
* Connection #0 to host localhost left intact
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