Handle vm_size choice in "Create an Instance" step

Use the variable passed in that the user chose for vm_size.

roles/cloud-azure/tasks/main.yml

@@ -80,7 +80,8 @@
     virtual_network: algo_net
     name: "{{ azure_server_name }}"
     ssh_password_enabled: false
-    vm_size: Standard_D1
+    # I have no idea how to use the variable I created and passed from Algo. Do I need this lookup stuff?
+    vm_size: "{{ vm_size | default(lookup('env','VM_SIZE')) }}"
     tags:
       Environment: Algo
     ssh_public_keys:
@@ -91,6 +92,8 @@
       sku: '16.04-LTS'
       version: latest
   register: azure_rm_virtualmachine
+  
+  # To-do: Add error handling - if vm_size requested is not available, can we fall back to another, ideally with a prompt?
 
 - set_fact:
     ip_address: "{{ azure_rm_virtualmachine.ansible_facts.azure_vm.properties.networkProfile.networkInterfaces[0].properties.ipConfigurations[0].properties.publicIPAddress.properties.ipAddress }}"