Add Loading Bar about spa HOT 2 CLOSED

So I've added in a circular loader with just CSS to keep it simple.

One issue I've been coming across is that the loading bar disappears before the content fully loads (on first load). I believe this is because the function ends first, then the HTML elements for the MAC addresses load after. For subsequent loads, the content loads right away and the loading circle disappears seconds after. This isn't a big issue, but I can fix this after we've merged everything and I'll go back an restructure the way modal loads.

On another note, I've chucked the loader CSS into modal, which I feel should be its own CSS file for cleanliness sakes.

Design choices, its currently a light blue quarter of a circle spinning on a grey background. Thoughts?

@RyanH1234

from spa.

Sounds good - we can go over refactoring on Wednesday, design choice sounds good

from spa.