Differentiate tabular datasets from regular datasets

[ridoo]

Already possible:

• Filter via API: /api/v2/datasets/?filter{subtype}=tabular&exclude[]=*&include[]=pk&include[]=subtype

More important to check and adjust workflows to handle tabular datasets:

• Download Handler
  • Downloading table data via the GeoNode download interface #4
  • Evaluate how components handle tabular data #6
• Metadata Editor
  • Support for attribute_set for detailed description of the dataset contrib_datapackage#10
• View metadata and details
• After changing metadata of nonSpatial Dataset its converted to geo Dataset contrib_datapackage#4