Added some UINavigationController spies
Updated nil checks in tests
Replaced text field and text view responder spies with UIResponder spy like it should have been in the first place
Added a UITabBarController spy
Reorganized file structure
Fixed a spy test
Added a UIPageViewController spy
Updated in-source comment formatting to match Swift
Added some UIWebView spies
Fixed a test name
Added some UIWindow spies
Added some UINavigationBar spies
Added a spy to UIToolbar