Implements injector and manifest

commit 03ce6991ce049a4a84eaa62514364850ed89217a
Author: Nestor Arocha <nesaro@gmail.com>
Date:   Wed Mar 19 10:53:58 2014 +0000

    implements Injectors

commit d97eaf9fd71537f9e19372c85e0eb223e153b48e
Author: Nestor Arocha <nesaro@gmail.com>
Date:   Wed Mar 19 10:16:37 2014 +0000

    added Injector and DollarExpression class