hdf5_ep

Merge pull request #239 in HDFFV/hdf5 from develop_merge_cache_image_05 to develop

* commit '8d4c84eae2954a77c725f42298b20d694a6150c8':
  Bring changes to metadata cache "get entry status" call and new "child serialized / unserialized" messages and support from the cache image branch.
  Add "image up to date" flag / parameter to metadata cache entry status calls.