Remove hard-coded dependency on named AWS credential profiles

[acannistra]

In #25 [045be20] I am removing dependencies on credentials in dockerfile. This likely changes the tutorial contents' dependency on having a configured profile.

Because of this, some tutorials (e.g. the sagemaker tutorial) should not reference a named profile anywhere, and should rely on properly configured runtime IAM roles (e.g. for sagemaker or EC2) to provide access via the AWS credentials metadata service.

Originally posted by @acannistra in #26 (comment)

[acannistra]

One way around this would be to create a default profile that uses metadata service (e.g. [here])(https://docs.aws.amazon.com/cli/latest/userguide/cli-configure-metadata.html) which users can change if they're running in an environment that doesn't have the metadata service available.

[acannistra]

See #26