Prevent staging site indexing in Google et al

[ejhumphrey]

the plan is to use a throwaway domain (e.g. http://ismir.rocks) as a staging site. We don't want it to be indexed by google, and a staging-based noindex tag needs to be added to the layout.html

good recap of the issue here: https://searchengineland.com/how-to-keep-staging-development-site-index-286987