Accept HTTP 20x as success, not error

[PavelVanecek]

Our server endpoint returns 201 HTTP status code, but filedrop.js considers this as an error and calls the error handler. Given the semantics, this should be considered success and call the file.event("done", ...) listener.

[crabhi]

Hi @ProgerXP, @bollwyvl, according to this commit, it seems intentional but I couldn't find any reason why should 2xx responses be considered failures. What was your use case?