* add cache to redis
move out cache module from mongo
* fix redis tests
* add callback noop
* fix typo
* del cache on field delete
* make redis/mongo caches separate
* [test/database/list] Fix test list 4 being used in two different tests
* [database/postgres] PostgreSQL database driver
* [database/postgres] Make transactions work based on continuation scope.
* [database/postgres] Implement nested transactions
* eslint --fix
* Add database changes from earlier this week to the PostgreSQL driver.
* Fix typo
* Fix postgres.incrObjectFieldBy returning undefined instead of null when given NaN
* [database/postgres] Fix sortedSetsCard returning an array of strings.
* Update socket.io postgres adapter
* Fix PostgreSQL erroring when multiple updates are made to the same sorted set entry in a single operation.
Add a test case to catch this error.
* Fix lint errors.
* Only prune sessions on one instance in a cluster to avoid deadlocks.
They're caught and handled by the database server, but they spam the logs.
* Fix arguments.slice.
Groups.destroy can take an array of groupnames
Groups.leave can take an array of groupnames
db.incrObjectField/decrObjectField can take an array of keys
db.sortedSetRemove can take an array of keys and values
db.setRemove can take an array of keys
* [database/*] Allow databases other than Redis to provide pubsub for clustering if Redis is not present
* [pubsub] Delay messages sent before the database is ready until the database is ready.
* [pubsub] Restore old behavior of not using the database in non-clustered NodeBB instances.
See comment: https://github.com/NodeBB/NodeBB/pull/6233#issuecomment-357814968
* cache mongodb objects
remove user settings cache since it is cached at the object level
* removed indexOf from isMemberOfSets
* change has to get, change maxAge to 0
