Add helpful error message if user does not have access to S3 bucket #16
Description
If the user tries to download from S3 bucket but they do not have permission to access the request object, the error message should provide details about the permissions needed and how to request them.
Suggested message:
You don't have permission to access this task. For more details about requesting access to the ML Bazaar Task Suite, see https://mlbazaar.github.io/#how-can-i-request-access-to-the-datasets. If you think you should already have access to this task, make sure you have configured your AWS credentials correctly.