Fixing Full screen with single story mode.
Fix #512. Hide immersive single tap preference on pre-4.4 devices.
Merge pull request #519 from manderson23/master

Fix #512. Hide immersive single tap preference on pre-4.4 devices.
New styles/font popover. Handles story titles pane, font family, and font size.
Adding Gotham Narrow, Sentinel, Whitney, and Chronicle.
Adding line spacing options.
Line spacing icons.
Adding single story preference.
Removing dupe preferences that now live in style popover.
Adding premium explainer (and disabling fonts) for non-premiums.
Adding H&FJ fonts.
Dev fonts.
Moving fonts.
Fixing title size, fonts in List view, date and content preview colors, and helvetica size.
Little less dark story date on unread west-side.
Moving fonts to www.
Updating fonts with semibold whitney.