Adds support for message queue triggers based on the NATS-Streaming message queue.
This lets the user map a queue topic to a function, and optionally send the function's response into another queue topic.
The message queue trigger manager is designed to be message queue independent, so we should be able add support for more queues by adding implementations for the relatively simple mqtrigger.MessageQueue interface.
Add function log aggregation and persistence using Fluentd and InfluxDB.
Fluentd and a helper sidecar run as a daemonset. The poolmgr sets up logging for each function pod, using the helper sidecar. Fluentd forwards logs to InfluxDB, which is run as a deployment and service. The client CLI directly queries InfluxDB for logs.
Fluentd supports many outputs besides InfluxDB, so we aren't very tied to InfluxDB.
The setup is somewhat manual, which we should be able to improve by integrating this into the helm chart.
Diagram of component interactions: https://cloud.githubusercontent.com/assets/202578/23100399/b0e3ea00-f6ba-11e6-8f2f-6588cfef2e84.png
