Add DailyHitTotals and their pre-computation tasks
Replace hits with totals everywhere there's a graph
Squeeze an extra second or three out of the big hitters

* Be explicit about quoting strings (this buys a surprising amount)
* Remove scopes moved to totals
* Remove the "grouped" scope, which was an accident continually happening
Merge pull request #58 from alphagov/total-hits-perf

Bring back Totals for hits