"Save as version" link for "HEAD" version of entity
Two better key names in entity version JSON
Rearrange project links to reflect better level of operations
Implement entity root handler

This handler returns JSON representing the content of the entire entity.
Skip authentication all together for now
Add more links for the entity root
Add dataset links to their parent group's links list
Fix a bug in group links list
Merge branch 'entity-root-handler' into develop