extdom: add support for new version
Currently the extdom plugin is basically used to translate SIDs of AD
users and groups to names and POSIX IDs.
With this patch a new version is added which will return the full member
list for groups and the full list of group memberships for a user.
Additionally the gecos field, the home directory and the login shell of a
user are returned and an optional list of key-value pairs which
currently will contain the SID of the requested object if available.
https://fedorahosted.org/freeipa/ticket/4031
Reviewed-By: Jakub Hrozek <jhrozek@redhat.com>