What we called 'links' are no longer returned in a container of
objects, they are top-level entity attribtues. This fixes the
parsing of the entities to look in the correct place when trying
to locate a specific schema.
Add a helper for printing to stderr and exiting with a non-zero
exit code.
Map 'name' to 'Attribute' when explaining a schema.
Related to bp glance-client-v2
Change-Id: Ib98e912a7af0bb570b4fd738733edd9b837d1a05