Proxy the description method in the same style as the others.
A failing spec for spying on weak properties referring to UIKit classes
Extract CDRSpyInfo class to manage associations

This replaces usages of objc_setAssociatedObject
CDRSpyInfos are released in +afterEach

Restores original class of spied object so that it can be deallocated
reliably if compiled with ARC.
Fixes errant CDRSpyInfo property declarations and adds missing dealloc.
Added test and renamed test object properties

NSObject subclass test added for completeness.
Weak property references renamed for clarity.
A spec change due to iOS 5+ARC weak reference bug