correct the way variables are recovered by ldap backend

adding a get_param method + pass backend name to backend

fix backend name (collision with libraries name)

begin ldap backend implementation

better logs

implementing loading backends ...

* fix conf file
* add exceptions
* fix modules skeletons

multiple modifications: ...

* adding logs in conf loading
* fixing attributes/roles handling in class LdapCherry
* fix unit test on logs
* add unit test for random exception

implementing backends parsing of main config file

init backends initialization method

displace _get_loglevel near othe log related methods

fix log_level + unit tests ...

* python logging doesn't support the 7 log levels of syslog, compensate it
* adding unit test on log level

adding loading roles and attributes

begin implementation of the main application

rename main class

adding get_attributes

change backend key name in attributes + methods ...

* adding get_backends
* adding get_selfattributes (attributes users can change themselves)
* adding unit tests
* rename backend-attributes -> bakends (for homogeneity with role.yml)

better checks for attributes

adding checks for mandatory elements of attributes.yml

begin attributes handling manipulation

add methods for class Roles + unit tests ...

* adding get_allroles (list all available roles)
* adding get_display_name (get display name of a role)
* add various unit tests

unit test + admin roles fix ...

* adding various unit tests
* now admin roles are inherited (ex admin-lv2 is admin -> admin-lv3 is admin
* adding an exception when requesting groups for none existant role

implementing various methods: ...

* get_groups (get_groups of a role)
* is_admin (determine if ldapcherry admin)
* get_backends (get list of role backends)

better comments and slight improvement in perf

fix in get_roles

implementing roles resolution from list of groups

implementing nesting roles

fixing typos in role files

adding an exception for failures to open role file

handling exception if a role key is duplicated

adding loading of the roles yaml file