Fixed Hosts form error message bug.

Liberated models from accepts_nested_attributes_for.
updated forms and js for waiters and hosts
Removed unneeded js assets.
Renamed hosts.js to something more descriptive.
Named the ajaxError handler in modal_forms.js
Added a preliminary ajaxModalSuccess handler.

Hopefully, we'll end up architecting away the need for it, by using
actual form submission ajax, as opposed to the Rails-y mess.
Cleaned up the modal_forms.js.

Made the function naming idiomatic js. Also fixed a typo.