Merge branch 'monthly-billing'

* monthly-billing:
  Allow the DB to notify us to bill a customer
  Command.execution setter
  Bill plan command
  Clearer name for lock bypass factory

Clearer name for lock bypass factory

LowBalance returns amount added, if any

Fix typo, add test

Merge branch 'overage-limit'

* overage-limit:
  auto_top_up_amount and monthly_overage_limit from CustomerRepo
  Move Bandwidth Tn remote operations to BandwidthTnRepo
  Use value_semantics to DRY up CustomerRepo
  Use NotFound exception for all customer not found cases

auto_top_up_amount and monthly_overage_limit from CustomerRepo

Move load of auto_top_up_amount to the repo, and load monthly_overage_limit in
the same operation.

No low balance if not registered

If cancelled or expired or not-yet-registered, don't auto top up or notify about
low balance.

Merge branch 'rubocop'

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

Switch to rubocop 0.89.1

This is the rubocop in new Debian stable

Bring in line with the key from billing_monthly_cronjob

Merge branch 'low-balance-auto-top-up'

* low-balance-auto-top-up:
  Some people have exactly 5 who don't need to be told
  On low balance, top-up or notify
  ExpiringLock helper

On low balance, top-up or notify

On start up, check for users with low balance and NOTIFY about them.  LISTEN for
such notifications and process by either sending a low-balance warning message
or else attempting an auto-top-up as configured.

Using NOTIFY/LISTEN because then we can NOTIFY after any INSERT that leaves the
balance too low (using a trigger).  Doing the sync on start-up in case we missed
a NOTIFY during any downtime.  Using the Redis lock to prevent spamming a
low-balance user in case of many restarts or if they have many small
transactions happen in one day.