fd_viewControllerBasedNavigationBarAppearanceEnabled should be defaulted to NO and should be honored in the viewWillDisappear method

When using this library it will create various issues since it is swizzling all instances of UINavigationController. The default for controlling the navigation bar appearance, fd_viewControllerBasedNavigationBarAppearanceEnabled, should be NO so that it doesn't conflict with other implementations. The user should specify if they want to turn this feature on.

Start by locating the UINavigationController category code that defines fd_viewControllerBasedNavigationBarAppearanceEnabled and the viewWillDisappear implementation. Check how the property is initialized and whether that lifecycle method consults it; done means the default is NO and the setting is honored without changing explicitly enabled behavior.

Written by the indexing model from the issue text.