Added DebugMenu listener

Listener that handles both direct observation of notifications or can register an observer and selector via the DebugMenu interface
I'd define macros in a separate header and make the log macro generic so it can be used elsewhere too:

```
RZDebugMenuLogDebug(s, ...) NSLog((@"[RZDebugMenu]: DEBUG -- " (s)), ##__VA_ARGS__)
```

You could also define an error log macro similarly but not disable it during release builds