Merge branch 'hotfix/backend'
Add locache to the application
Add unload methods and cache methods to MVC
Add default controller action for window unloads
Add default storage of loaded cells
Store and load main cell on window unload/load
Add version variable to MVC
Generate ID for catcher and fix non-Error typed errors
Notificate on subject, not parent
Return source when catching
Return error data when failing promise
Add main notification popover

For alternative actions when errors occur.
Add alternative action for cell no longer on server
Store cell on save
Add Rack::Offline gem
Fix PDF pages not being responsive
Add the mime type for stupid browsers
Move CSS images

On production, the paths could be different.
Hello appmanifest!
Remove console.log