Top downloads should be sorted

This bug applies to the current WebUI Analytics as well, in the "Repository Content" pill the Top Downloads are still not sorted correctly...

Old Description:

The demo for the nuxeo-audit-data element provides an example to build a top downloads list. But the items are sorted by document order, not number of downloads order. This is because they are sorted based on the results from the page provider, not based on the audit data.

https://github.com/nuxeo/nuxeo-dataviz-elements/blob/master/demo/audit.html

It makes sense that this list should be sorted by downloads I think.