Refine submission process

[jonthegeek]

Inputs: Data returned by calendar picker, possibly separately user info (see #100)
Return: Probably a click-counter-style value that can be used to invalidate other data.

Internally handles the button UI, disables itself when clicked, saves, then reenables itself. Might also display a "Selections saved" modal or something similar (might be a separate ticket, but the idea is that should be handled here).