drEnablement template has variable referencing itself

[drEnablement.json](https://github.com/Azure/azure-quickstart-templates/blob/master/azmgmt-demo/nestedtemplates/drEnablement.json)

### "sourceContainerName" (line 32) variable references itself

Line currently is:
"**sourceContainerName**": "[concat(variables('**sourceContainerName**'), '/asr-a2a-default-', parameters('vmresourceGroupLocation'), '-container')]",

I believe it should be:
"**sourceContainerName**": "[concat(variables('**sourceFabricName**'), '/asr-a2a-default-', parameters('vmresourceGroupLocation'), '-container')]",

Open azmgmt-demo/nestedtemplates/drEnablement.json and inspect line 32, where sourceContainerName is assembled. Confirm the variable reference uses sourceFabricName as described, then validate that the template no longer contains the self-reference.

Written by the indexing model from the issue text.