gmoc.py should allow submission of resources which have no aggregate

[chaos@bbn.com]

It is optional for a resource to have an aggregate set, so there should be a way to submit data for resources which have no aggregates. Right now, GMOCClient.store(obj) supports only:

• obj of type SliceAuthority
• obj of type Aggregate
• obj of type POP, in which case GMOCClient will iterate over SliceAuthority and Aggregate objects, and, within Aggregate, will iterate over Resource objects tied to that aggregate.

In addition, GMOCClient.store(obj) should support submission of Resource objects directly. (If it's easy, it would also be nice to iterate over all resources tied to a POP, not just those with an aggregate set. But that's not as pressing.)