Catch Exceptions instead of Objects in scheduler
Upgrade logstasher and correct typo

Logstasher had a typo on a config flag in version 0.2.5 (suppress_app_log was spelt supress_app_log).
Version 0.3 seems to have had the typo fixed, but also accepts the incorrectly spelt version.
Add debugger to fast_test_helper.rb
Scheduled publishing logs to separate logstash log

Introduces a new logger class for formatting log messages in Logstash JSON.

Logs to "<environment>_scheduled_publishing.json.log" which is configured
in scheduled_publishing initialiser.

ScheduledEditionsPublisher also now uses appropriate log levels.
LogStashLogger no longer mutates logged hashes