Add a 'saved' or 'saving' class to the edit page

[willdayble]

I'm a bit confused about how 'saving' for course + other edit pages work.

• Do we need a 'save' button?
• If we are saving with JS, can we do html classes?

NB: The classes I've made that can be used to indicate loading, saving etc:

html.loading_spinner html.loading_check html.loading_error

[willdayble]

And when we do any 'save', make loading_check appear, and then remove it after 3 seconds.