Stub AWS session in test
Stub AWS session in test

Problem:

Before this change, boto was looking for AWS creds specified via ENV
variables or a valid ~/.aws/credentials file. This was undocumented and
complexity to setting up a clean developer / CI environment.

Solution:

Directly set the `boto3.setup_default_session` in test/__init__.py,
ensuring that any downstream boto calls would use this session.

izakp/hokusai