Lazy dynamic accessors

I've lately started depending more and more on the lazy instantiation of a property's value, rather than injecting them at alloc/init by the injector. With the added `EEELazyInjection` category on `NSObject` it is super easy to trigger lazy injections for all properties you manually make @dynamic.

The category does not (yet?) take into account any protocols you have on your property, so it will apply to *all* dynamic properties. Maybe this category opens up other uses of the `EEEInjectable` marker protocol.