initdokku fails on "Please set a hostname for 127.0.0.1 in your /etc/hosts"

[dokku vm](https://github.com/azure/azure-quickstart-templates/tree/master/dokku-vm)

### Issue Details

We get this error when deploying the script to azure

```
VM has reported a failure when processing extension 'initdokku'. Error message: \"Enable failed: failed to execute command: command terminated with exit status=1\n[stdout]\nPreparing to install v0.10.3 from https://github.com/dokku/dokku.git...\nThis installation script requires that you have a hostname set for the instance. Please set a hostname for 127.0.0.1 in your /etc/hosts\n\n[stderr]\n--2018-04-27 10:58:23-- https://raw.githubusercontent.com/progrium/dokku/v0.10.3/bootstrap.sh\nResolving raw.githubusercontent.com (raw.githubusercontent.com)... 151.101.32.133\nConnecting to raw.githubusercontent.com (raw.githubusercontent.com)|151.101.32.133|:443... connected.\nHTTP request sent, awaiting response... 200 OK\nLength: 6603 (6.4K) [text/plain]\nSaving to: 'bootstrap.sh'\n\n 0K ...... 100% 73.1M=0s\n\n2018-04-27 10:58:24 (73.1 MB/s) - 'bootstrap.sh' saved [6603/6603]\n\nsudo: unable to resolve host DokkuVM\n\".
```

We can ssh into the box to edit the /etc/hosts file as it suggests, but then are unsure how to get the initdokku script to re-run ...

Start with the dokku-vm template and locate the initdokku extension command that runs during deployment. Reproduce the Azure deployment, inspect how the VM hostname and /etc/hosts are configured, and verify that initdokku completes successfully and can be rerun after a failure.

Written by the indexing model from the issue text.