Allow per-badge voting results

In some instances, it may be interesting or even necessary to see how different groups of users vote. This pull request adds the option to do so: instance administrators can select a list of badges that get evaluated. Currently, the implementation is somewhat limited and calculates the tallies on the fly, but it shouldn't have any effect without enabling it installation-wide.

Tracking issue: hhucn/adhocracy.hhu_theme#54