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.