[#44908065] Refactor make_api_uri() and add unit test for retrieving correct NodeSet list using NodeSetResource.
[#44908065] Assign owner to NodeSet instances created via Tastypie API.
[#44908065] Change GuardianAuthorization to deny requests other than GET and POST, code cleanup.
[Delivers #44908065] Switch NodeSetListResource to use SessionAuthentication and GuardianAuthorization.