mussel,test: add unit tests for image.
mussel,test: add unit tests for backup_object.
mussel,test: add "destroy" test for instance and load_balancer.
mussel,test: add unit tests for host_node.
mussel,test: add unit tests for storage_node.
mussel,test: add unit tests for network.
mussel,test: add unit tests for security_group.
mussel,test: add unit tests for ssh_key_pair.
mussel,test: add unit tests for "undefined".