Nuxeo-filters-behavior isMember method is not supporting subgroups

Reproduction steps:

1. have a group "A"
2. set group "A" as a subgroup of "powerusers" group
3. have a user "X" being put in the group "A"
4. authenticate with user "X"
   => the "Administration" panel is not being displayed

It seems the isMember method is only looking at direct groups: https://github.com/nuxeo/nuxeo-ui-elements/blob/v2.2.2/nuxeo-filters-behavior.html#L149