Clean up the UI a touch

Sorry for the mega commit, this really spiralled way out of control I'm afraid :/

- The first major point is that a lot of these line changes are for formatting, to make the code more maintainable in my opinion. In short I've added a ton of line breaks but I've kept the vast majority of the variable/function names and the general file structure :)
- Fixes a couple of bugs in aggregate_json_ui.py
- Removed a load of front end code, in particular unneeded HTML and CSS that was mainly in there for aging compatibility.
- Generally neatened up the edges of the UI really.
- Still needs work but I've started to split out the Javascript files from the HTML itself, same goes for the CSS.

Going forward there is still a bit of structural work to do, mainly I'd like to adapt the urls to be more meaningful and change the file structure behind them to be a little more intuitive for new developers.