Message queues: add support for delayed start (use :auto-start <ms> option)
Message queues: log notice on worker start/stop
v2.4.0-RC5
Scripts: fix b537a56 regression for vector (non-substituted) keys
v2.4.0-RC6
Tundra: return to earlier `fetch-keys` (over `fetch-key`) DataStore interface

This design requires a little more work from DataStore implementers, but allows
significantly more flexibility in a performance-critical area. Opens up a number
of possibilities incl. parallel fetches, composed DataStores, etc.
Tundra: expose public `>safe-keyname`, `<safe-keyname` util fns
Tundra: optimize Faraday, S3 DataStore impls for new `fetch-keys` API
Tundra: sanity check DataStore's `fetch-keys` result
v2.4.0-RC7
Tundra: code review, housekeeping
Deps: Nippy 2.5.0, Clojure 1.6.0-alpha2 (for testing), lein-ancient 0.5.4
v2.4.0