Added back the download stats, which got lost in a merge.
Provide a means of supplying the joint mappings in the FST file so that agent
scripts can address joints by name.  Closes #2526.
Merge pull request #2615 from ey6es/master

Add the download stats back (they got lost in a merge), provide a way for bots to address joints by name (by including indices in the FST file).