Make crypto module python3-compatible
* Remove usage of unicode() and decode the base64-encoded string in
encrypt();
* Encode the string received in decrypt() as (I supposed) it should come
from the result of encrypt().
Add tests for this module along the way.
[tox]
envlist = py27,py3,flake8
[testenv]
deps =
pytest
commands =
{envpython} -m pytest {posargs:test}
[testenv:flake8]
basepython = python3
skip_install = true
deps =
flake8
commands = flake8
[flake8]
exclude = cubicweb_%(cubename)s/migration/*,test/data/*,.tox/*