Merge branch 'rubocop'

* rubocop:
  Additional fixes for rubocop 1.10.1
  Switch to rubocop 0.89.1

Additional fixes for rubocop 1.10.1

This is the default rubocop in Guix.

Fix usage report range

Show things from all of the start of range (today)

Notify admin if a user goes over 500 messages in 30 days

Notify only once per day (using expiring redis key).
Can notify MUC or user, always sends directed presence first so it will join MUC
if not joined.
Ignore all messages direct to the component, mostly to throw out live messages
from MUC if we join that to notify.

Usage command

Customer has a CustomerUsage which can fetch data to build a UsageReport
which returns a jabber:x:data form "table" as per spec for per-day in
the last month.

Minutes come from cdr table in postgresql.
Messages come from redis.