Dependency Upgrades and Minor refactor

ChangeLog

• Badly formed channel messages result in 400 error
• When this service is shutting down, it won't be receiving any more messages
• When a message fails with 503, the caller should retry

1.0.1

Changelog

1.0.1 - 2017-08-08

• Add new MAX_POST_SIZE config var and env var set to default of 10mb