Sets up Travis CI tests to use a Kubernetes cluster on GKE. All tests have access to $KUBECONFIG which points at a kubeconfig file with credentials to a cluster.
I had to skip the poolmgr unit test because it currently assumes NodePort services; that will be fixed in another change.
Also, because some of the tests don't work properly in parallel, I've ended up reducing the concurrency to 1. If this becomes a problem we'll have to fix the tests, but for now I don't mind just waiting a few minutes longer.
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.
