Updates healthcheck endpoint

[ewilde]

Description

Updates health check handler to use new name

How Has This Been Tested?

• Ran against certifier see: Adds test for health check endpoint certifier#19
• Manually using curl

curl 127.0.0.1:8080/healthz -i                        Fri  3 May 14:43:11 2019
HTTP/1.1 200 OK
Content-Length: 0
Date: Fri, 03 May 2019 19:43:14 GMT

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have signed-off my commits with git commit -s
• I have added tests to cover my changes.
• All new and existing tests passed.

[alexellis]

Approved

[alexellis]

When the image is pushed, then this can be put into docker-compose.yml in the faas repo. https://github.com/openfaas/faas-swarm/releases/tag/0.6.2

[ewilde]

thanks @alexellis see: openfaas/faas#1180