title: CLI - Error when disk parameter is in use
body: <p>So i have a problem with softlayer vs creation, i try to create a vs from public image, but if i use --disk option i got an error.</p>
  
  <p>Command:</p>
  
  <pre><code>vs create -H g0 -D example.org -c 1 -m 2048 -d ams01 --image 3c289880-2f63-48d3-906d-aaa9a822a6d0 --billing=monthly --vlan-public 1313131 --vlan-private 313131 --disk 25 --test 
  </code></pre>
  
  <p>Error:</p>
  
  <pre><code>SoftLayerAPIError(SoftLayer_Exception_InvalidValue): Invalid value provided for 'blockDevices'. Block devices may not be provided when using an image template.
  </code></pre>
  
  <p>If i don't use --disk option it creates the instance fine.</p>