Need to have parent_aoi and sub_aois on AOI model

[jkeifer]

This issue references PSU-CSAR/vb-bagis-h#4. We need a relation on the AOI model to itself to allow parent-child relationships. The REST API should return a list of all the children of a parent, preferably with the ID and name.

RESTful practices probably prefers a hyperlink rather than an ID or name string, but the AOI URLs only have the ID in them; can the AOI URL have both ID and name, and be parseable by the desktop bagis?

[jkeifer]

One request in the referenced issue is to return an AOI ID of a parent AOI before the import task finishes, so child uploads can be started. Converting the model IDs to UUIDs (issue #7) allows pre-generating the AOI ID when the upload starts with very little risk of collisions. Thus, any upload response can contain the ID of the object to be imported, even the first time it returns--before the upload is even completed.

I am splitting the required work for this aspect of the request into a new ticket #11.

[jkeifer]

For my reference, it turns out this is only half completed. The fields exist on the AOI, but the create view method is provided by the generic UploadMixin. Thus, it does not call the new_upload view method with the appropriate arguments to actually set the parent_object_id on the upload that gets created. Additionally, the AOI create_from_upload and create methods have not been updated to include the the necessary arguments either.

The work is otherwise there, so cleaning these couple remaining issues up should implement this feature.