Setting port on serve doesn't seem to work

[chrisvfritz]

arch-cli serve -p 9292 or arch-cli serve --port 9292 both seem to ignore the port I pass it and use 3000 instead.

[chrisvfritz]

For more context, this one's a blocker for hosting on PaaS providers such as Heroku, where there's a $PORT or similar variable that needs to be used.