NATS Streaming is deprecated and will be removed from OpenFaaS
CE in a future release for security reasons.
Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>
NATS moved its primary library to: github.com/nats-io/stan.go
This commit synchronises the library in the gateway to match the
queue worker.
Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>