Feature/polling map 2

Finishes up the functionality of the polling map page by allowing the user to get directions via the maps app by tapping an location's infowindow. 

Also:
  - Refactors all of the error code in Elections+API.h to a new VIPError
  - Adds a bit of error handling/logging code in NearbyPollingVC
  - Refactors the geocoding functions to instance methods of the classes that need it