fix load more arrivals btn to always show results

* if no arrivals in next 35 minutes tells user
* load more arrivals button will search in 30 minute increments until it
finds new arrivals or it has searched 1 day in the future
* if no results for 1 day tells users
* adds loading animation for load more arrivals button
* adds loading animation for load more arrivals button when refresh is
occurring (rather than just disabling)
* fixes loading bar when searching through 30 minute increments for next
arrival
* changes load more button click color to blue so as to match other
buttons
* reduces magic numbers
* code cleanup