Possum

No functional changes, but the monolithin __init__ file has been broken up into numerous sub-modules for upcoming feature work.

Dependency updates.

Support for overriding S3 directory.

Converted project to a package for future feature work. No new features are included with this update.

Fixed a behavior where an error would be thrown if a `Globals` section did not exist in a template.

Support for SAM Globals, API Gateway Swagger files (via DefinitionUri key), and passing AWS environment variables when running in Docker.