* Refactor Expression.dimension to accept q

* Handle quarter- and half-hour timezones

Previously APIv2 output didn't start at a full hour for these time zones
and main graph was blank

The core reasoning is that ClickHouse `timeSlots` is not time-zone
aware and works off of unix epoch - meaning that in time zones which
have an offset of 5:45 the "hours" reported would start at minute :45.

The fix is kind of silly - we now divide each hour into 4 and handle
things that way.

Related basecamp issue: https://3.basecamp.com/5308029/buckets/36789884/card_tables/cards/7590936581

* Fix test typo