title: EJS error on es6 Template Literals
body: <p>I'm creating a Yeoman Express app generator and using a template js file that contains template literals. 
  I want the output file to contain this line</p>
  
  <pre><code>app.use(`/api/${apiVersion}`, apiRoutes); 
  </code></pre>
  
  <p>but I think ${apiVersion} is being interpreted as a template value and giving me the error</p>
  
  <pre><code>ReferenceError: apiVersion is not defined
      at eval (lodash.templateSources[2]:9:10)
      at copy.process (/.../node-microservice/node_modules/mem-fs-editor/actions/copy-tpl.js:11:58)
  </code></pre>
  
  <p>How do I get around this without having to just use</p>
  
  <pre><code>app.use('/api/' + apiVersion, apiRoutes); 
  </code></pre>
  
  <p>?? thanks!</p>