[Task] Change default proxy server port

[kmcginnes]

The proxy server currently defaults to port 80 for local development uses. Since port 80 is disabled on many OS environments for security reasons we should use a different default.

Risks

We will need to consider a few things when making this change.

• Experience of a user when updating from an older version
• Non-developer runtimes (i.e. Docker) should continue to use port 80
• Should be easily overridden by the developer (perhaps an environment value)

Related Issues

• Parent #403