Removed unneeded and obsolete methods. Added Cluster methods to get a node, all nodes, a instance, and all instances.
Removed unneeded and obsolete methods. Added Cluster methods to get a node, all nodes, a instance, and all instances.

alanjds/django_object_permissions,osuosl/django_object_permissions,alanjds/django_object_permissions,osuosl/django_object_permissions