add unit test for login failure

adding unit tests for demo backend

better unit tests on authentication

small code reorganization ...

* extraction of exception decorator
* extraction of log handling

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

fix unit tests

adding check function to validate attributes type

adding check for reserved password keys

adding unit test on selfmodify

remove trailing spaces

remove empty line

adding unit test for _parse_params

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

various fixes in html + unit tests on html

adding html validation in ubit tests

adding unit test for ppolicy

disable ssl in test configuration

fix test configuration

adding various unit tests

adding proper acl in test ldap configuration

fixing get_roles unit test

fix test ldap content

adding ldap groups to test group management

removing crapy configuration file

list of roles and not a uniq role for get_groups

reverse because no effect + disable ssl unit test on travis

fix decorator to disable check on travis