Only load CMS files if logged in

[notramo]

CMS components slow down the loading of the page. Some users don't need CMS (e.g. small amount of content on page, and editing by hand), so it would make sense to add a config option to not render the CMS in production.

[jimafisk]

Similar to #199. This brings up a great point though, not only is it good to be able to completely remove the CMS if you don't want it on a production site, but also CMS related files should only load if you're logged in. I'll update the title of this so we keep track of both issues.