Aggregation not working in ”pull request usage” chart

[pluehne]

Despite the fact that I implemented a generalized aggregation framework and enabled monthly data aggregation for the pull request usage chart. This isn’t visible in the live demo, whose TSV file has monthly data only. On a real appliance, where daily data is recorded, this becomes apparent:

Apparently, I introduced this bug in #105. The code responsible for aggregation is now only called for multiview charts (but the pull request usage chart has a single view currently).