Add a check on the length of replies and outbound SMSes.

[hodgestar]

The check would be on a configurable maximum message length (set in the config for the JS app) and would log a warning if the content is too long.

The test harness already checks this but a check in production would help pick up odd errors (e.g. where the aggregator ends the USSD session because the reply is too long) more quickly. Sometimes production replies are longer than test replies (e.g. because dynamic content is included in the replies).