Extend the health endpoint and add gateway version information

Resolves: #733
Signed-off-by: Edward Wilde <ewilde@gmail.com>

Signed-off-by: Alex Ellis <alexellis2@gmail.com>

* - Extend stack to include a test function
* - Allow _ char in routes
* - Let Dockerfile shrink by coming from alpine

* Update build.sh

* Document stack deploy

* Update README.md

* fix port in README (#3)