The JSON-Schema of integer string is without min length limits. That
leads to the user can input empty string, and nova API code can't
handle that case. Finally the user will get 500 returned.
The create_backup and multi_create API are fixed. The networks and
tenant_networks API have same problem on few parameters, but due
to the nova-network is deprecated, so just keep those nova-network
specific API behaviour as before.
Change-Id: I521e914fc48b7a221431f41c567f2cb4b9b4ab99
Closes-bug: #1652719
934ccef0bd