add inheritance to getting properties for class

Hi! It's me again. Today I encountered a problem, that method: 
```objc
+ (NSDictionary *)propertiesForClass:(Class)cls
```
returns properties only for current class, wthout inheritance.

I spend for about 5 hours to understand, why my object saves to nsuserdefaults not fully.
I added some recursion for superclasses of current class before NSObject in objects hierarchy.