Model Uploader Recursive

[akshayj-MSFT]

1. Added a feature for -d to delete all models
2. Added major improvement so that if Model is not found - it recursively looks at Model references (in extends and in properties/components) and loads them first - and does this recursively (REC models don't need this, but other models, e.g. Willow models did)

[alinamstanciu]

@akshayj-MSFT this is great, thanks for making this change, could you please change the readme to reflect this changes, including -d option? Thanks