For ldap, try to get secondary groups from LDAP query

[Olivier Sallou]

in case of ldap auth, would be nice to get secondary groups directly from LDAP instead of using local system (though could be used as fallback). This would avoid need to know local users on system, especially with containers

[Olivier Sallou]

ldapsearch -x -b "ou=Groups,dc=test,dc=org" "(&(cn=*)(memberUid=XXX))"

[Olivier Sallou]

add new optional config param:

ldap_base_dn_group_filter: 'ou=Groups'

in goauth, try to get groups with search in groups with user in memberUid if no result, try to get from local host as previously as fallback solution.

[Olivier Sallou]

try to get secondary groups from ldap when possible, closes #49

→ <<cset 81f69a07b8cc>>