iWeekly's font size and line spacing setting

Have added this function to the Android version. App Store's moderation is so painful recently.

The app is live on Play and App Store:

Play: https://play.google.com/store/apps/details?id=com.rakutec.android.iweekly

App Store: http://itunes.apple.com/cn/app/iweekly-zhou-mo-hua-bao/id453405026?mt=8