Improves the error message when we get an HTTP error response.
Improves the error message when we get an HTTP error response.

Jesus/dropbox_api_v2,Jesus/dropbox_api,luigi-sk/dropbox_api,Jesus/dropbox_api,Mavvie/dropbox_api,luigi-sk/dropbox_api,Jesus/dropbox_api,Mavvie/dropbox_api,Jesus/dropbox_api_v2,Mavvie/dropbox_api