Support typical image request format(s)

[deliahu]

E.g. multi-part image requests

When moving body and form params into the payload object, also consider adding query params

Related to #546 if the solution here is to expose form data in the handers/predictor

Notes

# multi-part form
curl -F 'image=@dog.jpg' 'http://a276ec846ff2211e9b92c0a56b992336-830038469.us-west-2.elb.amazonaws.com/iris/classifier?debug=true&test=2'

# form
curl -F 'image=test' 'http://a276ec846ff2211e9b92c0a56b992336-830038469.us-west-2.elb.amazonaws.com/iris/classifier?debug=true&test=2'

logger.info(request.args)  # query params
logger.info(request.form)  # form
logger.info(request.files)  # multi-part form

• https://flask.palletsprojects.com/en/1.1.x/patterns/fileuploads/