groups#show: also display members for groups with more than 1000 members.
caching: trying to catch another marshalling error.
Use jquery datatables for group_of_groups views.

trello: https://trello.com/c/saXLsVwH/675-groups-of-groups
quick fix: group of groups: use first(4) rather than limit(4) on Array of officer groups.
group of groups view: also list officers of descendant groups; fix caching problem.
giving a healing potion to a randomly failing spec.
making #find_officers_parent_groups_of_self_and_of_descendant_groups faster.
group of groups view: fixing caching in haml.
users#show: Aktivitätszahl nicht in Großbuchstaben umwandeln.
new model cache: removing old `cached(:foo)` calls.

Caching is now handled by the called methods rather than the caller.

See „Caching“ in the repo’s wiki.
abilities: users can only see pages of their groups.

picked from 12126eb1d7919bfdb943757a748be60094b91f75.
abilities: check if the user is admin of anything to avoid the detail check for non-admin users.

Picked from 12126eb1d7919bfdb943757a748be60094b91f75.
fixing groups controller spec.
what's-new box: only list pages the user can read.
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.