Adds weak reference support to set of injected objects stored inside the injector. This is to ensure injected objects no longer referenced are GCd.
Include InjectedSet.delete for backwards compatibility and add simple test to ensure injected objects are added to the attendedToInjectees set.
add a little documentation
Rename InjectedSet to InjecteeSet
Merge pull request #3 from massiveinteractive/weakref-support-for-injectionset

Avoid Storing Strong References to Injectees