Organic group (OG) Permissions inherit

Setup hierarchical relationships between ogs so that og members can inherit
og permissions from it's lineage.

For example, Lets say we have a series of og courses managed by og course admin
members and each og course had a series of og tutorials run by og tutor
members and that we wanted the og course admins to be able to administer
the og tutorials. This module negates the need of adding the og course admin
users as og tutor admin members. Instead they will inherit the permissions,
enabling them to have the same privileges lower down the tree.

* With this module you do not need to keep adding users at each level of the
tree and then giving them new roles and permissions at that level.