Refactor app to use AppSettings.h
Basic styling for most view controllers

Begins the styling process with the following:
  - Proper UITabBarItem colors for normal/selected states
  - Darkens the UINavigationBar to the dark blue of the top of the bg
    image
  - Sets the bg image for each view controller via a superclass
  - Sets the default UILabel text color to white for all UILabels
    inside a UITableViewCell
  - Proper header colors for Ballot & Details views
  - Styled about this app section