Add  a white preroll cover to the storefront.  Remove it once all images are loaded.
Preload theme's CSS background images when opening the store
- Storefront: load template from hardcoded path unless an overriding base URL is provided
- Backyard: inject the base URL when loading a model and delete it when saving \ generating.  It's temporary just for the purpose of the current design session so that the template will be loaded correctly
Merge branch 'decoupleThemeDir'