Given that PEP 0414 was only implemented on 3.3, Python 3
of version 3.2 and prior is not supported, as it would be
cumbersome to add, and 3.2 is used by few anyway.
* only bibtex format is supported
* all tests except test_repo.py and edit test pass
* edit and update commands were not updated
* removed --format argument from export, only bibtex is supported.