[172 MUX] Bugs

These are all bugs accidentally created from #172 

* Clicking directly on the select checkbox confuses the jQuery
* Checkin procedure checkboxes get toggled as well

Solution:
* [x] Add hidden class to checkbox (so user cannot click it)
* [x] Add check icon to selected reservation cards, to give additional visual feedback when something is selected
* [x] Fix jQuery to only select the first checkbox (or the only hidden box)