Merge pull request #510 from dosiecki/master

Android: Bugfixes
If user is current and premium, don't recharge card. Otherwise, create a new customer.
Fixing unicode issues in text importer. Closes #224.
Allowing alt emails to grab paypal payments.
Showing content previews and boosting font size on story titles on web.
Adding preference for showing/hiding content previews.
Only showing content previews if they are different than the title.
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.