Previously, if metadata-store said a graph existed, we'd unconditionally scry
for it. Now, we make sure the graph actually exists, to avoid risking a crash.
Scrapes groups and graphs for member counts and recent activity respectively,
and uses that to print out a "tally" of activity for all local groups and their
channels. Since this output is intended to be shared with other parties,
anonymizes resource identifiers by default.
