Master: Fix unsynced test for empty buffers
Add `/api/stream_groups` endpoint; Rip out more old listeners code

* Add `/api/stream_groups` endpoint to list groups and sources
* Rip out more of the old slave-reported listeners code
Put test redis config on a different db
Analytics: Query against the proper date-based index range

* Add `_indicesForTimeRange` function, which returns an array of indices
  corresponding to the chosen time range, making sure our queries don't have to
  cross too much data.
* Store session time as the last listen, not the start time. Cleans up sorting
  and is more in-line with traditional logging