Version 2.2.0

This is a new feature release and is backwards compatible with all 2.x releases.

Notable changes since 2.1:

• PM::TableScreen: You can now set a custom table view header view (thanks Mark Rickert)
• PM::TableScreen refreshable: Refresh controls now show when programmatically initiating refresh (thanks Mark Rickert)
• PM::TableScreen: Added reorderable (thanks Mark Rickert)
• PM::TableScreen: Added auto height feature (thanks Carlin Isaacson)
• PM::Screen: The navigation controller bottom toolbar will auto-hide when passed nil or false (thanks Mark Rickert)
• PM::Screen: You can now choose a status bar style (thanks Mark Rickert)
• Added on_load and on_styled hooks for UIViews that implement those methods (Jamon Holmgren)
• Fixed an issue where cell properties would be applied twice unnecessarily (Jamon Holmgren)