Add group objectclass to allow AD nested group search.

The objectclass of an Active Directory group is 'group'. Without this, it doesn't recurse into sub-groups because the `group?` check fails.

Also bumped version to 1.3.5 (I don't know if that's appropriate or not).

I've tested this locally against enterprise-manage (not running as part of a GHE appliance), but not against github itself.

See also https://github.com/github/github/issues/31742 and https://github.com/github/github-ldap/pull/40