Use name links instead of permission links to include objects in groups.
Expose names for owned_items as list_response.name_for() in Workbench
Convert joins to subqueries to fix duplicates in owned_items
Fix patch_paging_vars args.
Skip UserAgreement in owned_items. They are just collections again.
Rename owned_items to contents, remove user method, update docs.
Merge branch 'master' into 2640-folder-api
Add partial unique index
Merge branch 'master' into 2640-folder-api

Conflicts:
	services/api/app/controllers/application_controller.rb
	services/api/app/models/arvados_model.rb
Fix log permission case broken in merge.
Use partial unique index for name links.
Merge branch 'master' into 2640-folder-api
Fix wrong infixes in fixture uuids.
Add unique and valid name constraints.
Name links do not need to be owned by tail_uuid.
Fix crash if item has no name (backported from 1970-folder-view)
Return empty list if no "links" supplied in api response. Add tests.
Return all links if link_class is not provided. Add docs.
Improve code formatting
Prevent ownership cycles.