Cr/feature/log when skipping delegated methods

We ran into some confusion using this because (though the reason behind it makes sense) it is not obvious that certain delegate methods will be skipped unless all children implement them. Adding a logging statement both warns new users of this library that it is a requirement to implement these methods for all children, and also (as in my case) is a useful tool when refactoring to make sure all the bases are covered.

Also I included the Kiwi cocoapods upgrade because the tests passed, but just let me know if you want a new clean PR without that.