title: Remove empty field's name from document
body: <p>I've been able to add a large volume of empty keys in a MongoDB collection. As empty keys is not allowed in MongoDB I'm having a hard time to unset the key using regular methods in MongoDB. Is there a workaround for this kind of problems using mongo shell?</p>
  
  <pre><code>{
      "foo": "bar",
      "": "I should not exist, I have no key..."
  }
  </code></pre>