Bug 20006: Unit tests fixes

Bug 20006: Unit tests fixes

This patch makes the holds endpoint tests pass and expect data structures that match the voted RFC.

As we voted to introduce a /public namespace for unprivileged access to
endpoints, this endpoint gets the ability for owners and guarantors to
manipulate holds through the API.

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
(cherry picked from commit 52bb9802dda6f6bb3619cc6d8e921ecd8175c8ce)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>