543 home page ui tweaks

[DO NOT MERGE] hey @pld, i would appreciate feedback on the approach I used to make the ajax requests
since this both shows and hides it's probably better named `toggle-loading-modal`, because it does not return a boolean it [should not end in a question mark](https://github.com/bbatsov/clojure-style-guide#naming)

(I haven't been consistent about this but that is the only time a function should end in a question mark.)