Prevent older versions of Chrome from appending a Content-Type header containing the Blob type, rendering the request invalid if we intend not to provide a Content-Type. This behavior was observed in Chrome 58.
Direct upload on firefox is not working because it can’t handle click
events on “input[type=submit]”.
After a successful upload we can see on console a xml parse error, it
happens because AWS S3 success body response is empty, so changing the
reponseType suppress this error.
