Added changes to the metadata layer to support plugin metadata implementations.
Merge pull request #955 from jamespentaho/5.0

Added changes to the metadata layer to support plugin metadata implement...
Merge pull request #956 from tkafalas/5.0-feature

 [BISERVER-10202/10203] Changes to import allow DSW metadata files to be  imported into metadata.
[BISERVER-10202/10203] Fix unit test failures related to
MetadataImportHandler