2.2.0

• A DatabaseProvider interface has been added to facilitate mocking of
  DatabaseReader. Pull request by Yonatan Most. GitHub #34.
• A getLeastSpecificSubdivision() method has been added to the
  CityResponse and InsightsResponse model classes. This returns the
  least specific subdivision for the location, e.g., England for Oxford,
  GB. Pull request by Daniel Kaneider. GitHub #35.
• The InsightsResponse and Location classes are no longer declared final.
• AbstractResponse is now declared abstract.