Option to change default stage

[tj]

For side projects like https://gh-polls.com/ there's not really a need for staging, just opening this issue to get a better idea of how many people would like an option to default up to production etc. Just leave a thumbs up.

[kaihendry]

Was caught out by alerting only working on production stage https://github.com/apex/up-examples/blob/master/pro/alerting/Readme.md