title: JS Render interpreting hyphen in property name as subtraction sign
body: <p>I'm using JS Render to iterate over some data which uses hyphens in property names.</p>
  
  <p><code>{{:image_one.sizes.natural-massive}}</code></p>
  
  <p>That is returning a NAN result because it's attempting to run a mathematical operation. How can I force JS render to treat that as a string?</p>