Structureable: providing #admins_of_self_and_ancestors. Also testing its caching behaviour.
fixing failing specs after modifying Structureable#delete_cache.
refactoring abilities in order to make the checks faster.
profiles: only require the :update ability rather than :curd to show edit buttons and to show empty boxes. This is because a user should not have the ability to delete himself. This has been clarified in the last change of app/models/ability.rb.
allow users to request a new password from their profiles' account box.
caching: adding spec for turning User#global_admin on and off.