Nested stacks are missing outputs

[dsalavei]

I've been trying to use kinesis-firehose-cloudwatch-logs-processor as part of my kinesis firehose stack, but because all Serverless applications get deployed as nested stacks there is no easy way to reference the resources in the parent stack if there are no outputs. For instance, "serverlessrepo-auto-subscribe-log-group-to-arn" application has outputs and can be easily integrated.
I strongly believe that before being published the applications need to have the resource outputs specified in the template.

Overall, I'm loving the Serverless Repo!