fix load more arrivals button to always show results

* If no arrivals in next 35 minutes tells user:
![photo 3](https://f.cloud.github.com/assets/1192780/1234339/6d8a10a0-296c-11e3-9abd-b73d667e4d45.PNG)
* 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
    * If there was no results when load more button was pressed:
![photo 4](https://f.cloud.github.com/assets/1192780/1234340/97b2336c-296c-11e3-9d79-7ef82bcb9a16.PNG)
    * If there was already results when load more button was pressed:
![photo 5](https://f.cloud.github.com/assets/1192780/1234341/a171ff7c-296c-11e3-847c-413c83f52998.PNG)
* Adds loading animation for load more arrivals button
![photo 1](https://f.cloud.github.com/assets/1192780/1234344/ad23c256-296c-11e3-9ddb-c7e441287bbd.PNG)
* Adds loading animation for load more arrivals button when refresh is occurring (rather than just disabling)
![photo 2](https://f.cloud.github.com/assets/1192780/1234345/b73497b6-296c-11e3-8acd-d3e273ca04cf.PNG)
* Removes loading bar when searching through 30 minute increments for next arrival since we don't know how many 30 minute incruments we will need to look through
![capture](https://f.cloud.github.com/assets/1192780/1234349/e509d1e2-296c-11e3-97a9-3dd8c874fddb.PNG)
* Changes load more button click color to blue so as to match other buttons
* Reduces magic numbers
* Code cleanup

Tested:
* With and without filters
* Disabling and re-enabling filters
* Report a problem > with a bus
* Successfully cancels load more request when:
    * Closing app
    * Locking app 
    * Switching to a different view
* Navigating to view from:
    * Map
    * Bookmarks
    * Trip schedule