Update backend DataSet Model to support annotating datasets
Add metadata for:
Column level descriptions (could be in the JCR store for the schema)?
Projects (see related ticket )
Feeds (already exists)
For this sprint added
Descriptions/tagging/column level descriptions
Added a separate user story for linking to Projects: KYLO-3240
Postponing support for Notes to later phase. Notes was meant to be some form of support for user discussion/comments which we should think through not just for Datasets but for any other entities.