[#1002] Remove dependency from chevah.utils

Problem description
===================

We want chevah.empirical to only depend on chevah.compat 

In this way it all code for testing "chevah.utils" package will be moved in chevah.utils.


Why we got into this (5 whys)
=============================

chevah.empirical came from chevah.commons which came from chevah.server ... so many code was mixed.


Changes description
===================

All chevah.utils imports were removed and code specific to chevah.utils package was removed.
It will be moved in chevah.utils in the #1002 branch fro chevah.utils


How to try and test the changes
===============================

Nothing special here.