What I would suggest as requirements/functionality: 

• On the Admin/Customize page have a checkbox for allowing types (Showing them on the ui)
  If the type is enabled: 
• Add a managing dataset types per instance (Clowder) or per space page. A page similar to the metadata definitions page. 
  • If it is per instance, add it to the admin dropdown
  • If it is per space, add a button below the customize metadata terms and definitions 

 Note: I prefer for it to be per instance, and only admins of the Clowder instance can add possible types.

• On Create a dataset a dropdown with the types for the instance show up.
• The type would be listed on the dataset page below created on
• There will be an edit button near the type which shows on hover. When clicked a drop down with the options for the  space/instance show up