Research: On-the-fly averaging, by week only

[ecumike]

Investigate and test "pick a week" report detail page scoping for the two averages tables; KPI and user-timing.

Allowing "week of ___" data scoping may be performant enough to do on-the-fly because it's only grabbing 7 runs and averaging them.

Test how bad the query would be to do on-the-fly date range scoping averaging of a URL's runs with a database of at least 7,000 URL records, each with 60 runs (two months of test runs data).