Flask-annex

- **Bugfix:** Stop using `Annex` as a proxy to the underlying implementation (23)
- **Bugfix:** Raise an exception in `FileAnnex` if `root_path` does not exist (25)
- **Refactor:** Use the actual `from_env` method on each annex class in `Annex.from_env` (23)
- **Refactor:** Remove abstract base class use in `AnnexBase` (23)
- **Refactor:** Use Boto3 for S3 support (24)
- **Test:** Add test coverage (24)

- **Feature:** Make S3 access keys optional (20)

- **Refactor:** Use vendored compat module instead of six (11)
- **Chore:** Set up proper publishing and build scripts (11)

- **Bugfix:** Fix content type handling on S3 (10)

- **Bugfix:** Always send files as attachments (9)
- **Bugfix:** Improve handling of filenames (9)

- **Feature:** Support file-like objects in addition to filenames (8)