All index controller timezone fix

The crux of this change is to adjust datetimes to UTC in two places: before calculating the next day's date and before assessing the 'sameday' condition for two dates.

Tests all pass but in the course of loading updated responses from CAPI I had to re-create some new data entries, and tweak the expected result values in old tests. Manual testing showed that the fix had the desired effect but this has (so far) only been run locally.

This is one that @gklopper will be interested in.