Reduce size of email log messages
Count `log().error` calls with the Telemetry API

The log().error function is now wrapped so the number of times it gets
called (and from where) can be tracked through the Telemetry API. This
will allow us to put Nagios checks in place that measure error rates.

In the future statsd hooks could be put in place as well.
(Collections) Initial collections work
Minor comments cleanup
Tests + fix for invalidating the cache for getIndirectMemberships
Minor collections cleanup
remove tenant delete endpoints
drop deleted column on Tenant
clean up failed merge
Enable telemetry during tests + PR #999 followup
Merge branch 'email-log' of https://github.com/simong/Hilary into email-log
Removed unused require in content-search
Merge branch 'collections'

* collections:
  Removed unused require in content-search
  Minor collections cleanup
  Tests + fix for invalidating the cache for getIndirectMemberships
  Minor comments cleanup
  (Collections) Initial collections work
Moved tenant-delete-propert migration to 7.3
Merge branch 'removetenantdelete'

* removetenantdelete:
  Moved tenant-delete-propert migration to 7.3
  clean up failed merge
  drop deleted column on Tenant
  remove tenant delete endpoints
Update README.md to reflect extra steps for Etherpad configuration after skinning work
Follow up after review