Helper script to create Service Principal, Storage Account, Batch account

[jafreck]

The script should:

1. Donwload and install the Azure CLI
2. use azure cli to login
3. create a service principal
4. create a storage account, and give service principal access
5. create a batch account and give service principal access
6. validate success
7. save secrets to .aztk/secrets.yaml
8. delete azure cli

The user should provide azure login credentials, but should not have to know or provide any other information.

The user should be able to configure service principal, batch account and storage account values. Default values for all should be configured.

This can be executed with an aztk cli command. Something like aztk init.