@ mention of reviewers

@Didayolo

A brief description of the purpose of the changes contained in this PR.

This new feature is for uploading a task. A zip file with task.yaml and zips of datasets/programs are required to upload a task

You can use already existing datasets/programs by using their keys in your yaml. Check the following two valid tasks:

You can also use a mix of keys and files

Click the upload task button in the tasks tab in the resource interface to start uploading a task zip

Select a zip file in the filed field and click upload to finish uploading

I renewed the resource interface documentation including task upload here: https://github.com/codalab/codabench/wiki/Resource-Management

[ ] use the provided zip files to upload a task
[ ] try to break the uploading by planting errors either in files, keys or the yaml file

You can use the following files to test that uploading fails when there are problems: