refs #8221🔥 Remove ghost=true concept from asset url helper
✨💯 Introduce CSS minification with cssnano
- add new grunt-cssnano dependency
- wire up grunt task to minify public/ghost.css
🎨 Rename minification config & hash params
- Change minifyInProduction -> hasMinFile
- this means this asset should have a .min file available
- Change minifyAssets -> useMinFiles
- this means that in this env we want to serve .min files if available
🎨 Update public/ghost.css to serve .min for prod
- add the new `hasMinFile` property
🎨 Move minified asset handling to asset_url util
- this logic should be in the util, not the asset helper
- updated tests
📖 Error handler always needs asset helper
- this removes the TODO and adds a more sensible comment
- we also need to update our theme documentation around error templates
🔥 Don't use asset helper in ghost head
- use getAssetUrl util instead!
- removed TODO
📖 Update proxy docs
🎨 Simplify asset helper & add tests
- this refactor is a step prior to moving this from metadata to being a url util
- needed to skip some new tests
🐛 Add missing handler for css file
refs #8126, #8221, #8223✨ New 'Proxy' for all helper requires
- this is not currently enforced, but could be, much like apps
- the proxy object is HUGE
- changed date to use SafeString, this should have been there anyway
- use the proxy for all helpers, including those in apps 😁✨🎨 Single instance of hbs for theme + for errors
- we now have theme/engine instead of requiring express-hbs everywhere
- only error-handler still also requires express-hbs, this is so that we can render errors without extra crud
- TODO: remove the asset helper after #8126 IF it is not needed, or else remove the TODO
🎨 Cleanup visibility utils
🎨 Clean up the proxy a little bit
🚨 Unskip test as it now works!
🎨 Minor amends as per comments
