Refactoring, fixes, and improvements.

Fixes #50.
Refactors out `TabsAdapter` into its own class.
Refactors locations management into `VoterInfo` model.
Alerts user if address if not geocoded, instead of showing map at (0,0).
Add tests for location list management
Merge pull request #51 from flibbertigibbet/feature/activity-refactor

Feature/activity refactor