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.
3.26 (1 February 2018)
======================
New features
------------
* For ``pyramid`` instance configuration kind, logging is not handled anymore
by CubicWeb but should be configured through ``development.ini`` file
following https://docs.pylonsproject.org/projects/pyramid/en/latest/narr/logging.html.
Backwards incompatible changes
------------------------------
* CubicWebConfiguration method 'shared_dir' got dropped.