[Feature request] client-side check for the submission api

Can we have a client-side inplace check that asserts if submitted file is indeed a zip archive?

Recently I faced [the issue](https://github.com/Kaggle/kaggle-api/issues/503) that prevented me from submitting the .csv to the competition, and the API provided vague error, so I suggest you to improve error message in this particular case.

Also I think it's possible to make client-side check rather than make user wait for an upload and only then provide the error.