title: How do I give imageNameRegex an actual regular expression
body: <p>I'm trying to use a specific AMI on AWS using it's name.</p>
  
  <p>It works if I set <code>imageNameRegex = region/image_name</code> but fails if I try any of the following:</p>
  
  <pre><code>imageNameRegex = image_name
  imageNameRegex = .*/image_name
  imageNameRegex = .*image_name
  imageNameRegex = /.*image_name/
  </code></pre>
  
  <p>The aim here is that I can copy an AMI across a number of regions and have Brooklyn pick up the correct one without my having to specify a specific image id for that region.</p>
  
  <p>Looking at the Brooklyn tests then I shouldn't even need a regex - as long as the name is a substring of the full name it should work.</p>
  
  <p>I'm setting this in the <code>brooklyn.properties</code> not the yaml all though I can't imagine that makes any difference.</p>