fix test and exception handling in code ...

With python 2 it was possible to do exception[0][...] to recover
details about an exception.
It's no longer authorized with python 3.
Now, we must do something like exception.args or exception.urls.
fortunately this syntax also works with python 2.
So we use it for both.

fixing the test env deploy script + small fix in unit tests

porting the tests over to python3

remove useless tests

small cleaning

improve robustness if user dn attribute contains something like ,cn=

more unicode testing

fix many encoding errors on login and password

fix unit test on duplicate user exception

multiple modification/fix ...

* add display_name parameter for backend
* handle display_name in modify template (lonely groups) and error
  message
* fix bug in modify when user is in only one backend
* remove redondant exception in ad/ldap backend
* fix unit test accordingly
* fix License in AD backend (GPLv3 -> MIT, previously tought of using
  samba4 python library which is GPL, but this module finaly uses
  python-ldap which is MIT compatible)

adding utf-8 char in unit tests for ldap backend

remove trailing spaces

remove useless test

various fix on ssl/tls + tests ...

* making ssl cert check and cert no check works
* adding a test to check if the cafile does exist
* reenable and fix ssl checks on travis

adding various unit tests

reverse because no effect + disable ssl unit test on travis

adding unit test for starttls

fix path to ca

reenable ssl no cert check

test for travis

more logs

greater timeout

fix unit test and fix the way ldap connexion options are handled

adding test for add/delete groups

small reorganization

fix and add unit tests on ldap backend

adding key handling

add unit test for get_user

adding unit test for del user if user don't exist

add unit test for get_groups