History view across multiple submissions #78
Description
Currently, there are a few places to view the history of a single submission. I'd like to have a new menu that let's me get the history of all the submissions in a single assignment group and view them the same way. This should be a separate route for the assignment_groups endpoint. You can look at the blockpy endpoint's browse_history function to see how that handles things. You can also check out watcher.ts in the frontend to see how that works and renders. I'd like most of the logic for this to be in the frontend Knockoutjs application side, rather than using the jinja2 template approach. Obviously, the backend controllers and models should handle extracting out the events.