Problems with Dokku deployment

[Deploy a Dokku Instance](https://github.com/Azure/azure-quickstart-templates/tree/master/dokku-vm)

### Issue Details
I have a problem with deploying this template on Asure. I've contacted MS support and they claim that the issue is with the json script:

> "extensions": [
>
> {
>
> "name": "initdokku",
>
> "type": "Microsoft.Azure.Extensions.CustomScript",
>
> "typeHandlerVersion": "2.0.3",
>
> "statuses": [
>
> {
>
> "code": "ProvisioningState/failed/0",
>
> "level": "Error",
>
> "displayStatus": "Provisioning failed",
>
> "message": "Enable failed: failed to execute command: command terminated with exit status=100"
>
> }
>
> ]
>
> }
>
> This is the Json being deployed, Line 215 they invoke CustomScript to run a script deploy_dokku.sh during VM creation:
>
> https://github.com/Azure/azure-quickstart-templates/blob/master/dokku-vm/azuredeploy.json#L215
>
> which is where that error above comes from.

### Repro steps (*if necessary, delete otherwise*)
1. I tried several regions (USWest, West Europe) and got the same error everythere during the deployment

Start with dokku-vm/azuredeploy.json at line 215 and inspect how the CustomScript extension invokes deploy_dokku.sh during VM creation. Reproduce the Dokku deployment in a region such as USWest or West Europe and investigate the reported exit status 100. Done means the template provisions successfully without the CustomScript extension failure.

Written by the indexing model from the issue text.