Existing code was only getting instances scoped to the user's
current token. When calling from the admin volumes view, this
needs to get all instances to correlate volume attachments.
Changed get_volumes to pass all_tenants=True to be consistent,
cinder ignores the value anyway and only looks for the all_tenants
key.
Fixes: bug #1193002
Change-Id: I5ed2a63997126911d6657619b062acd2947d06e1
73e62610cf