Add ip to create-github-command so browser opens on Linux

[Waterdrips]

Description

The linux use for the new create-github-app command didn't open the
browser and point it to the correct place, it just left the url blank.
This change means the browser opens correctly on Linux.

Signed-off-by: Alistair Hey alistair@heyal.co.uk

How Has This Been Tested?

By building and running, as shown below:

heyal@heyal-xps:~/go/src/github.com/openfaas-incubator/ofc-bootstrap$ go build && ./ofc-bootstrap create-github-app --root-domain ofc.heyal.co.uk --insecure
Name: OFC suspicious montalcini6        Root domain: ofc.heyal.co.uk    Scheme: http
Launching browser: http://127.0.0.1:30010
Starting local HTTP server on port 30010
Please complete the workflow in the browser to create your GitHub App.

Checklist:

I have:

• checked my changes follow the style of the existing code / OpenFaaS repos
• updated the documentation and/or roadmap in README.md
• read the CONTRIBUTION guide
• signed-off my commits with git commit -s
• added unit tests

[alexellis]

Lgtm

[alexellis]

Thank you 🙏👍🤓