Change Annotation handling

[eywalker]

In the running design, Annotation type lives in its own directory, separate from the object it's annotating. This makes moving the target object with annotation difficult. In the new design, Annotation will directly live in the resource folder that contains the target resource. For example, an annotation for a pod would be found as follows in the filestore:

pod
  └──hash
               ├── spec.yaml (Pod resource info)
               └── name-version.yaml  (annotation yaml)

Exact specification of the annotation file name is YTD but multiple annotation files would be allowed.
This issue is related to #27 as a resource may lack any annotation yaml, making annotation optional.