Sling Models: ResourceResolverInjector is obsolete

the "ResourceResolverInjector" can be considered as obsolete since Sling Models 1.1 because it is superseded by the "SlingObjectInjector"

attached is a patch that removes it and redirects the unit test to "SlingObjectInjector": remove-resourceresolver-injector.patch

there should be no problem witch backward compatibility - save one (rather hypothetical) issue: the ResourceResolverInjector checks only for the field name "resourceResolver", and not for the class. so if a user has defined a field of type "Object" named "resourceResolver" it worked with ResourceResolverInjector, but will not work with SlingObjectInjector. but i suppose this would be a very uncommon usage.

justinedelson please decide if we can remove the ResourceResolverInjector or should leave it.