officers: do not show input for direct officers if there are subgroups. otherwise, the admins might be tempted to enter redundant information.
using sidekiq to delete caches asynchronously in background.

trello:
https://trello.com/c/71kbkAYE/696-cache-leerung-nach-sidekiq-auslagern
removing fnordmetric worker. we did not get fnordmetric running correctly.

* https://github.com/paulasmuth/fnordmetric/issues/171
* http://stackoverflow.com/questions/20263883/fnordmetric-my-toplist-gauges-disappear
namespacing sidekiq redis store in order to support several stages on our server.