Use custom list adapter for contests.

Fixes #18
Do nothing if user taps info window for user address.
Add election picker to home view

The behaviour is as such:

If there are other elections in the response,
display the election picker and make another
voterInfo query with the same address when the user selects
another election.

Removes the election picker from view when a voterinfo query
is received that has no other elections in its response.

Added a few tests for VoterInfo/Elections models
Merge pull request #23 from CloudNiner/feature/election-picker

Add election picker to home view
Refactor ContestAdapter
Merge pull request #24 from flibbertigibbet/feature/customize-contest-list

Use custom list adapter for contests.