title: switch off scientific notation in Gson double serialization
body: <p>When I use Gson to serialize an Object that contains a double value close to zero it is using the scientific E-notation:</p>
  
  <pre><code>{"doublevaule":5.6E-4}
  </code></pre>
  
  <p>How do I tell Gson to generate</p>
  
  <pre><code>{"doublevaule":0.00056}
  </code></pre>
  
  <p>instead? I can implement a custom JsonSerializer, but it returns a JsonElement. I would have to return a JsonPrimitive containing a double having no control about how that is serialized.</p>
  
  <p>Thanks!</p>