[test] Re-implement generative tests with subtests

[devtools] Re-implement generative tests using subtests Generative tests as implemented in logilab.common.testib are not compatible with tests runner other than lgc.pytest and this implementation differs from the standard library, which has support for subtests_ since Python 3.4. Use unittest2 to bridge the gap. Maybe it'd be good to implement this on logilab.common.testlib side at some point. Let's see how this gets received here first. .. _subtests: https://docs.python.org/3/library/unittest.html#subtests

cleanups

[pkg] python-tz does not exist in centos should be pytz (closes #10290056)

[test] Skip LDAP tests if any of the underlying programs is not found Some programs are in ldap-utils or ldapscripts, which may not be installed despite slapd may. Follow-up on 282880f81311.

Handle virtualenv development mode Looking for VIRTUAL_ENV environment variable as a sign of virtualenv activation. This at least works for developing CubicWeb itself (not sure yet about cubes). And it makes `tox --develop` work as well. Add a test for cwconfig._find_prefix within a virtualenv. In tox.ini, use `develop option`_ accordingly. This makes tox running significantly faster since it avoids building and installing the sdist. Aside, the "develop" install is now performed *after* all test requirements are processed, which means that the cubicweb package should always be the one from source -- instead of a released version pulled by a cube through test dependencies, which may occur in "recreate" step. .. _`develop option`: <http://tox.readthedocs.org/en/latest/config.html#confval-usedevelop=BOOL

[skeleton] Use os.walk in setup.py for Python3 compatibility

[skeleton] Use unittest.main directly Instead of lgc.testlib.unittest_main as they are identical.

[devtools/testlib] Disable pause trace in setUp Closes #9856028.

[test] Remove dependency on person cube in devtools package