CLC-2883 HotPlate messages should never expire

https://jira.media.berkeley.edu/jira/browse/CLC-2883

The ttl setting in the TorqueBox::Messaging.publish call was causing messages to expire before they were processed. The special case of HotPlate is that we always want those messages processed. This pull also makes it easier to monitor (through /api/stats) how many requests are made and how many are processed. It also increases the default ttl (used for live-updates and feed-changed message channels) to 30000ms.