Managed Identity fix for Azure Runbooks

[andikrueger]

At the moment, managed identities are only support for Azure VMs. Within Runbooks there are issues with the used EndPoint to get the authentication token. This PR introduces a change that will enable runbooks to get the correct endpoint url.

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This change is 

• FIXES #146

[andikrueger]

@mlhickey could you test these changes in your environment?

[mlhickey]

@andikrueger - probably, but it'd be at least a week out given current commitments

[andikrueger]

Thanks for the response. I’ll spin up an virtual machine and verify the solution.

[andikrueger]

I was able to confirm functionality in AzureVMs.

[ykuijs]

@NikCharlebois, can you please review, merge and release a new version?