Upon unserialization from session scope, objects should be re-injected

[bendavies]

Upon unserialization from session scope, objects should be re-injected to populate no serializeable objects that may have been unset using __sleep or the overridden serialize()

[rodnaph]

This isn't entirely straight-forward as some dependencies may have been serialized with the object in the session. So when fetching back from the session we only want to re-inject any dependencies that have not been serialised.

At the moment the injector doesn't provide this fine a control over injecting individual properties or methods, so there will need to be some refactoring around there to make this possible.